I run the pc680 and it starts up perfect everytime, as well as runs all of my accessories. I've had it down for well over a week at a time and it has always started right back up again. I love it so far. It allowed me to actually run an intake with my intercooler piping without having to relocate the battery. Also, I live in Tucson, so it's dealt with some pretty high temps over this past summer and it's still performing like new. I got it at the beginning of summer, so I can't say that it's lasted especially long, but to say that I haven't had any hard starts at all with such a small battery is a pretty good feat to me. But seeing as how you have some amps back there you'll want something bigger. One of the larger oddyssey batteries might be up your alley.
Good luck!
Then again, I do understand why everyone is iffy about them. They aren't made to handle all the stuff we'd be throwing at them. But I'm gonna see just how long I can keep this thing down here in this heat.