UPDATE Nov. 16, 2007:
As of the last year or two, there is now a tuner that fulfills the seven criteria listed below. It is marketed under the name Meisel and Intelli (note, not Intellitouch), and has been widely adopted in bluegrass circles. It's squarish and small with a good swivelable clip, and an easy-to-read green backlit display. And it's inexpensive, often selling for about $30. I've also seen a similar tuner sold under the Barcus Berry brand name. This is now the tuner I recommend and use in all but the most demanding situations.

Bob,

Your question is a perfectly timed opportunity for a new product evaluation for my web site, so this will be it:

I can now give product reviews to five tuners, having used three for years, and now using a fourth. I also have tried the Intellitouch, but not for very long, as its appearance/inconvenience doesn't meet my needs. Many other tuners are both not instrument-mountable and not quick and precise enough.

For years now, I have been eagerly awaiting arrival of the Ultimate Compact Instrument-mounted Tuner. The state of the art keeps inching ahead, but we’ve still not found the *ultimate*. The ultimate would be instrumented-mounted and have:

1. Instant, exact, unwavering reading once the attack has registered
2. Easy sound isolation of the instrument being checked, total isolation if possible
3. Easy readability, even in direct sunlight
4. Battery-operated, with automatic shutoff
5. Calibratible to outside 440
6. Not an eyesore or an inconvenience if always mounted on the instrument (allows strap to be tucked around)
7. Inexpensive, easily available

The Korg AW-1 ($59.95) mounts on a banjo *only* with a certain type of clip invented and marketed by Gryphon Stringed Instruments, a music store in Palo Alto, CA. They sell the special clip (sort of like a springloaded toilet paper axis, notched at the ends to clip onto the rim brackets) for $15, with clear instructions. I found it physically tricky to mount, but now it holds the tuner in a convenient place.

The tuner is like a lot of tuners that often give an ambiguous, drawn-out first response, and need to be tried again to get a sort-of-believable answer. That means I can't use it when tuning *must be exact and fast*, like most gigs. A bummer, as it means for most gigs, I need to bring my no-longer-available Conn Strobe Tuner, which is large, fragile, hard-to-pack, and must be plugged in -- the kind many luthiers still use.

But for most conditions (indoors or shaded, not requiring a fast and very exact answer), the AW-1 is a good tuner to leave mounted on the banjo, thanks to its tiny size and great convenience. So I'll use both it and the big Strobe sometimes, and sometimes the battery-operated (but not mountable) Boss-12H, which is the quickest, most reliable battery-operated tuner I have seen.

Comparing the AW-1 to the Wittman:

1. Instant, exact reading: Both are poor in this respect, often requiring more than one hit on the string to get a clear answer, and usually not quick. The Wittman gives a slightly more exact answer when given the time. Intellitouch also poor, Boss 12-H better, Strobe wins hands down.
    
2. Easy sound isolation: AW-1 wins over Wittman, with an easily-switched-on Piezo pickup that gets sound directly (or if preferred, from a tiny mic). About a tie with Strobe, 12-H, Intellitouch.
    
3. Readability in any light: Wittman wins, as the display is just red or green tiny LEDs, readable in any light environment. AW-1 is a non-backlit screen, slightly cluttered display. Wittman also wins over the Strobe, which is not easily read in sunlight. Wittman ties with 12-H. Both slightly ahead of Intellitouch.
    
4. Battery-operated: They're both battery operated, but the AW-1 has automatic shutoff, a very big advantage, and an easy-to-replace battery. That advantage is shaded a bit by the battery's rarity, a dime-sized item only findable at stores like Radio Shack. The Wittman uses a good old 9V, but that has to be mounted *inside* the banjo, supposedly by velcro on the resonator (which tends to not hold, especially with airline flight case handling). I ended up taping the 9V to the coordinator rods inside the banjo so it wouldn't keep coming loose. But then when the battery gets spent (can easily happen if tuner gets left on, as by the strap flipping the switch when you put the banjo away), it's a hassle to change it: remove and replace the resonator, untape and retape a fresh battery. Now I should mention that the Wittman does have a sort of battery-left-on signal: It keeps flashing red lights whenever it hears anything, which does tend to get your attention.
   
   By contrast, the AW-1 rarely needs a battery change, and the change is simple to make: pull the tuner off its clip, open compartment on back, and battery slides in and out. Spare batteries are a few bucks, and one or two can be kept in your case compartment. All in all, the AW-1 wins this category, over the other competitors except it ties with Intellitouch.
    
5. Calibratable: The AW-1 is, and quite easily; the Wittman isn't. This is not important for most people, but it is for me when I play with Flexigrass, as we tune to the 442-tuned (no, I don't know why) vibraphone. Ties with other tuners. Most are calibratible.
    
6. Not an eyesore or inconvenience: Neither the AW-1 or the Wittman is either, which is part of why they both beat the Intellitouch and my Conn Strobe Tuner for most situations. The only howevers: Both tuners are mounted where I normally tuck the strap when casing my instrument. That can turn the Wittman on (and drain the battery) or nudge the AW-1 off its clip. The two tuners are about evenly rated here, well ahead of the larger Strobe and 12-H, and the uglier-on-instrument Intellitouch, that still has to be put away when casing the banjo.
    
7. The AW-1 and Wittman tuners are both priced at about $60, though the AW-1 really should have the $15 clip from Gryphon. Slight edge there to Wittman (and Intellitouch) with 12-H a bit more, and the Strobe not available except as a used item, plus costs there probably at least $200. Both tiny tuners take some doing to install. But small cost differences and installation are one-time factors, and in my mind, minor considerations when making such an important choice.

My 1979 Conn Strobe Tuner, used throughout Hot Rize days, and on into the 21st century, is my tuner of choice for gigs where I MUST be right in tune, as quickly as possible. Disadvantages: Must be plugged in. Must have wheel turned manually to note being checked (and wheel needs larger letters). Must be shaded in full sunshine. Large and fragile, with fixes costing over $100, only available by ONE company, Petersen, in Illinois. And so must be packed with padding when traveling. But since it gives me an INSTANT, EXACT, EASY-TO-READ, UNWAVERING answer, it beats all when seconds must be saved, and exact tuning is a must. If this tuner broke, I would find another one on ebay and buy it ASAP for important (i.e., most) gigs.

Bob, for you and people like you, valuing convenience and price, and rarely needing extra-quick, precise tuning, and rarely needing to use it in direct sunlight, I would recommend the Korg AW-1 somewhat over the Wittman, and the others. For those willing to use as their one tuner one that does not mount on the instrument, the 12-H wins, as it has all but auto-shutoff, and works more quickly accurately, and in any light. Or a person might have the AW-1 for most situations and the 12-H for backup.

So says Dr. Banjo! I hope the above helps.

Pete