I've been using a NanoKontrol for years and the small footprint and basic features are great, but its beginning to wear out, so I invested in the Studio version, thinking that the bluetooth feature would be useful to liberate a USB socket on my laptop when necessary.
Problem is, you can only connect via bluetooth. Plugging in via USB only provides power, not signal. And this BT connection requires an extra app installed and an extra step to connect. More things to go wrong in a live situation. Range isn't great and I've experienced a few disconnects. Also, I have a suspicion that the battery drains when the device is switched off.
It would have been nice if it worked the same as the NanoKontrol, but with optional bluetooth and a few extra buttons.