Nice. Stone Breath really is awesome.

Yeah that Lv 3 Key Sphere is relatively well known. In fact, in one of my playthroughs, I sent Kimahri down Rikku's path, got a Master Thief armor from the chocobo race at Remium and equipped it to Kimahri. With it, he always stole 2 Key Spheres. I got 20 Level 3 Key Spheres from that battle and they turned out to be pretty useful.

Pretty good setup overall. I like how you can build Kimahri however you want.