well if ya can hover the SR and looking for more stabilty a 450 class would work. But to answer your question bigger is better when it comes to stability. So a Raptor 30 is a 550 class heli and a .50 is equal to a 600 class.both will be alot more stable and easier to train on then the SR. So my advise is go as big as your wallet can afford just keep in mind what ever you buy make sure you leave some room in budget for repairs. As for gyro there many good ones out there imo just stick with the brand name ones such as FutabaAlign to name a few.