I've got both fences and VGs on my 173FGE. The VGs have been since day one and make a big difference. The fences have been on about 15 hrs. They appear to have shortened takeoff by about 200+ft, increased climb rate and provide a more stable approach to land at low speed (80-90 kts). I did lose some roll rate, no apparent change in cruise speed Bill S. 173FGE