The FunFighter series of RC planes are, as the name suggests, a whole lot of fun but it seems that the stock ESC just isn't really up to the task of handling a 4S pack.
Richard's one died on only its second 4S flight -- so we fitted a HobbyKing 30A ESC and now it's flying as good as it did before.
If you're going to buy one of these great little planes, I strongly recommend that you include a 30A HK ESC with your order because, even with a 3S pack, the stock controller does get pretty warm and the HK one seems a whole lot better.