I've had one of these for a year as a drummer and used it in live situations many times.
1.You really need the related Tama holder as well, so get the package if available. A small piece of thin rubber material between the holder and the Rhythm Watch will clamp it solidly. It's easily fixed to any convenient 10mm rod.
2. The battery will of course give up when you haven't got a spare, so get the 9volt DC adapter. This has to be CENTRE NEGATIVE which is not usual, but your friendly guitarist may have a spare. When this is plugged into the Rhythm Watch it bypasses the battery which remains on full charge.
3. If you now tape down the tempo tapping counter to permanently "On" it keeps the backlight on permanently, instead of going out after 10secs. This is great for on stage use.
4. The mode selector at STAGE is useful. Listen to the tempo then join in with four (usually) stick clicks which kicks off the band. The metronome stops after eight bars and if that is too long it's easy to switch off anyway.
I tried using headphones but personally find them too fiddly, but the option is there. Volume controls are loud and variable. I have programmed our stage sets into the machine easily enough, and if you need to change the numbered order or change the tempo, it can be done on the fly with the press of a button, or the large control wheel.
One feature that should have been included would be the ability to store all the variations of subdivisions into each songs memory, but that's not much of a loss.
Overall a great metronome with features that you can explore, and make good use of. A professional piece of kit that's well worth the money.