Scott,
I'm a  jazz player, and find that tap tempo is my most
important feature of arranger kb's. In fact, when I first started playing these things around 2000 (strictly a
sax/vocals man before that) I got a great deal on a
Kn2000 at a Mars store, which i thought was a great kb, but I soon returned it because no way i could gig solo without tap tempo.  I just have to start every tune with the groove I am feeling at that moment, not a preset tempo or have to fiddle with a wheel to get to where i want it. I have used a Korg is35, Technics kn2600, and Genesys pro S, and the tap tempos vary in their operation. the Korg is the best, will pick up after 2 taps..the others take 4, and the
Gem will start playing with just the key action, no need
to hit start button. I don't like that part of it, because
sometimes I want to tap in my tempo, then start a tune
with an intro out of tempo, then hit the start in tempo.
It took me a while to get my tapping to produce the
groove I wanted. I was inconsistent at first and couldn't 
understand why..but it is definitely not the fault of the
hardware but the tapper. the suggestion to tap another
surface or count out before you execute the tap button is
a good one, but i found this to be even more reliable:
Like modern golf putting instruction, use the large
muscles..the small ones are unreliable and inconsistent.
So if you go from tapping with the finger alone,  the hand (wrist) alone,  the arm alone from the elbow, each of those will be better..but the best is to groove with your body and keep everything from the shoulder or even the waist
as one piece with the fingertip as the end of the fulcrum.
Happy Tapping!
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Miami Mo
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Miami Mo