What should I be looking for when selecting an MPG dongle? I'm using a Gecko G540 and Mach 3.

I found 4 so far:

https://www.youtube.com/watch?v=q7aLiMDHQrM
https://www.youtube.com/watch?v=Z910AXJj8xo
https://www.youtube.com/watch?v=oA_JDPKp3tI&t=8s
https://www.youtube.com/watch?v=qTMDMipkZ5o&t=598s

I'm leaning towards the Tormach knockoff 'Shuttle'. Main reason is, do you really need all those buttons that you see on the Chinese ones? Also I like the double wheel i.e. inner wheel is fine control, outer is rapid. I also like that it's on a cable. I don't really want wireless, recharging is the most annoying thing in the world I think. One question that comes to mind about it is on the Chinese ones, you have the Off position for the axes. Do MPGs generate pulses when a program is running? Do you really need the off position? There's obviously no off functionality on the Shuttle.