i to am running a home made rigger and have similar problems to you Simon
i think props have a lot to do with it and testing out lots is a good start!
also strut adjusting is fun to play with as well! not that i have any clue as to what it does!! lol
im Brushless on mine and lipo batts and the power is there ! i just have the heat prob and thermal cutout aswell
just ordered an X637 metal prop as up to now i run with CF or plastic
nice log by the way -good to see your still at it
good luck