What I'd look for in a second plane is something that will fly almost as slowly as a trainer, but with reduced self-righting ability. You should be able to set the controls to respond about like the trainer, then turn it up as you get used to the plane. A light wing-loading is one indicator of how slowly a plane will fly. The H9 Funtana may in fact fly slow, but it's likely to respond much faster than a trainer and have zero self-righting ability. The Sig SSE is the same--it could be a good second plane, but it won't get you out of trouble. It's not a bad idea to look for strong landing gear and maybe the ability to nose-over without damage.