Chinky, my saito 125 hovers my ucd that weighs 7lbs 12oz easily at somewhere around 3/4 throttle, i use a apc 16x5 prop and get about 8800 rpm. im not wure how much your plane weighs but maybe this will give you some idea how the 125 performs, i like mine.
as far as the wing rock, ill let someone else chime in, ive never been able to cure mine on my ucd60.