My Horus has at last arrived. I love it! FrOS seems very capable, and they have a Github area where you can ask for additions or modifications to the software if required, which I've never seen another manufacturer do. Loads of options for flight modes, and it'll even run an 8 servo wing with ease. It even has a rotary position switch, which will suit the big quadcopter's changing flight modes.
An amazing amount of telemetry screens which is great for my big scalies, including vario, GPS, airpseed, voltage from up to 14 sources, temperatures, speeds, RPM etc etc. Should be a bonus for when I get the Pik20 sorted for GPS triangle racing, and also super for the ASK18 when she goes up behind a tug again.
Time for some more programming!