On a race bike it would be great. On a street bike pretty useless and unnecessary.
I feel the same way....unless it is simply because you have a disability in your left hand.
Actually, it is my understanding on that shifter there is a sensor in the shaft, so when you move the lever, it will produce an engine-kill of a few milliseconds to allow you to shift at any rpm, but.....there may be certain rpms and gears of which it may be finicky, requiring a longer engine kill. If this is incorrect, please let me know, as I'm constantly tryign to learn more about various shifters, full and partial.
If you want to talk about shifters with a REAL purpose, I'd be willing to talk...
I installed all three of those, as they are on my wife's bikes. I also have installed one on an SV650.