I have the same gimbal. The only problem I experienced was failure of the 5Volt regulator on the control board. I think I paid about $16 for a replacement board that needed to have firmware flashed to it.
You have to be very cautious of attempting to play with the firmware on these gimbals as many have a hacked version of SimpleBGC flashed on them. Attempting to tune with a legitimate version of the SimpleBGC software will trash the gimbal.
When I replaced the board on my gimbal I experimented with the opensource BruGi software but I found it rather tedious to get the gimbal's operation just right. After some searching I found a modified version of the Alexmos sketch which allowed me to use SimpleBGC to tune the gimbal so it would perform the way I wanted.
For the money, I paid $80 from Goodluckbuy which included shipping to the UK, they are a reasonable performer albeit a little heavier than other offerings.
Regards
Nidge