I use a slim for everything other than GT5 ( which is mostly media-related stuff ) because it's quieter. A guy at my work asked me if I could fix his old PS3, and I told him I'd give it a shot. Later he told me that he picked up another one, so if I fixed it, I could keep it. Turned out to be a $25. power supply, so I keep it in the back room with my obutto for playing GT5 and 3D Blu-ray movies.
I kind of wish I had just left it at the old firmware and sold it for a few hundred bucks, looking back on it. It's backwards compatible and was still on FW 2.2 ( or whatever it used to be where you could use the alternate OS. )