The Donald Takayama Scorpion look like they might be a bit of fun but probably more for smaller waves.
www.surfboardsbydonaldtakayama.com/surfboards/shortboards/scorpion/I had a Rusty Dwart for a while and liked it a lot (before it was nicked out of my garage). Packs loads of volume but again it's intended for smaller surf given that it has very flat rocker and fat, boxy rails. The Hypto Krypto is a similar shape but with a more of a pulled in tail. I haven't tried it.
As others have said, don't bother with the Firewire Sweet Potato unless you want a specialist short board for small mushy waves. I've had a go on one of these and they are perfect for mush but not intended for a lot else given that they are as flat as an ironing board.
I have a Firewire Spitfire now. It's certainly more capable in bigger surf than the Dwart but if you want something for over surf over head and a half then you may want a more pulled in tail while retaining plenty of volume under the chest area (the Spitfire has quite a wide tail). Saying that, it's the board I use the most when I am not on a long board.