The one thing I might suggest is providing a shorter Refresh Interval in the Advanced Options menu, eg as little as 20 or 40 msec if possible, then the servo responsiveness would be maximal.
Easy to do... let's see...
My next task is learning how to write my own Android BT apps. BTW, can you tell me which tools you used?
Android programming is a fascinating universe
Three very different approches are available on the market, with increasing learning curves
App Inventor
A full graphic cloud based application, just fitting together puzzle pieces
still in development, very intuitive but a bit limited for the moment
Basic4android
using a syntax MS Visual Basic syntax, creates native Android applications
Eclipse + Android SDK
for full blown applications, a bit frustrating at startup 
A first experience with Java will definitly help
Tons of help and snippets, at XDA developpers
lots of tuto's on Youtube
I tried App Inventor and finally choosed the hard way... 8)
this afternoon, we loaded Joystick Commander into a friend's Samsung Galaxy 3 cellphone running Android 4.1, and it worked perfectly in commanding my BT-Arduino1284 board and servos, so everything good. He was impressed, and not even an Arduino guy.
Thanks for this excellent feedback 
Out of curiosity, where is the Land of sun+snow ??