If you go with the Kaos, set up the control throw very mild. I flew one once and it was a handful. I don't think it was set up right because it was the most twitchy plane I ever flew. I think they are great planes, but they were designed for getting into pattern flying. I would highly recommend the Kaos for a fourth or fifth plane.

For unlimited vertical, you can't beat the profile planes. I like the ones from Morris Hobbies and most of the guys on the fun fly forum agree. Hang an OS 46 FX on them with an 11-4, 11.5-4, or 12.25-3.75 prop and they'll go up forever. A computer radio is highly recommended as you will want to dial some exponential into those large control surfaces.

I think a profile plane would make a good 3rd or 4th plane. I still think the best second planes are the Sticks and the Sig Kavalier.