The HK retracts are in my 50cc ESM LA-7. The Sierra rotators are in a Skyshark 55cc P-40, and the Robarts are in a TF giant P-47. They all work very well.
I agree you don't want to buy inexpensive gear that doesn't hold up and/or doesn't work. So far the HK gear have been a success...time will tell. The worst luck I've had with electric gear was a set of Robarts. They were repaired by the factory twice and never did work for more than two flights in a row.