This has been very intresting to read this thread sinve I have exactly THE SAME PROBLEM! I fly homebuilt Y6 with avrotos, APC 1238SF on top and 1260EP on bottom, 4S 5000mah or 8000mah. AUW 4,2kg with canon 550D and a crappy gimbal. I have iOSD (mark I) and 5,8ghz 200mw vtx and a ccd cam for fpv...