@jamesbeat
I have a 8Bitdo Zero, and can share some info with you...
I wonder if it would work well with android cellphones? Might make a nice pocket system.
Yes. It works with android. I use it with RetroArch and I'm very happy!
I don't know if I would want to use it as my main controller for extended play though.
It's not cool for fighting games. It's the only exception.
I can play Battletoads (NES) nicely with it, but it's hard to make a Shoryuken(Street Fighter), for example.
I'm sure I have seen a Bluetooth snes controller replica though.
If you are talking about the 8bitdo SNES30, then yes! It's very worthwile. I have a NES30 too, really really cool to play with those controllers. The 8bitdo company has some nice products there.
Conclusion: 8Bitdo Zero is cool, the only exception is for games where you need to do crazy stuff with the d-pad (eg: The King of Fighters special moves). I use it to play NES classics and I'm happy. It's cool to always carry in your pocket and play with your Android/RetroArch whenever you have opportunity.
BUT if you want to play at home, and have enough money, the SNES30 would be a better choice. It works fine with Android too, but it isn't as portable as the Zero.