Like most FBL systems if set up correctly they just work. German manufactures are generally very good with electronics They tend not to promote their products on a grand scale as Germans generally are not SMAK pilots but fly
Artistically as demonstrated by Simone.

 

I had 2 of the first versions (GT5).. .they flew well..

I got rid of mine as the first ones had no failsafe and I wasn't comfortable with that and they were not firmware upgradeable.
The new 5.2's do have it I believe and are also firmware upgradeable...

A friend of mine - "Dave" - who flies some very mean 3D had one of the early ones as well on an E-Raptor I recall and it flew very well indeed.

They take a bit of getting used to but once setup, work well..
Whatever you do, don't change the calibration settings in one of the menus as then you'll have to re-calibrate it and that's a pain in the but to do..