I flew the Typhoon 2 RTF this weekend and loved it. (been flying the OG Typhoon since it was released with stock battery, TX, and servos...still a fun plane...)
My initial setup was with the pushrods in the outermost holes on the control horns and no SFGs. Noticed the hum of the digital servos, but that's to be expected. Left the antenna down while a buddy held the plane, performed a range check, and headed out.
Plane flew well, seemed to be easier to hover than the original Typhoon with the heavy 9 cell Ni-MH pack. Without the SFGs it'd knife-edge just fine but needed a little elevator to keep it tracking straight. With the pushrods in the outer holes of the control horn I had no problem flying 3D on low rates. Flipping to high rates really made the Typhoon come alive. Fun, fun, fun.
Brought her in and installed the SFGs, repeaked the pack, and headed out for testing with the SFGs installed.
Tracked a bit better in normal flight, but seemed to be more sensitive to wind (cross-wind especially) with the SFGs.
With the SFGs installed I noticed that I had to use much less rudder to maintain knife-edge - proof that they're working. Knife-edge loops are cake. The SFGs do work. So well, in fact, that the same rudder inputs that I'd used to KE without them would result in the beginnings of a KE loop. At that point I'd just back off the throttle and transition into a hover like I meant to do it.
Roll rate is slightly decreased with the SFGs but nothing that most folks in the target market of this plane would honestly think twice about.
Harriers seemed to be a bit better with the SFGs, both upright and inverted...just pay attention to the wind direction.