I have a 1200 too, and I agree with the screws. I took out all but one row of them.
300 is a piece of cake to clean, you lift up on the front and pop it off. One giant filter. Couldn't be easier.
My friend has a p183 and it has major cooling issues. The sound deadening is worthless because you have to run so much fan speed to cool it down anyway. He's got a PII965 and 4890, so not a powerhouse by any means.
If you like the P series, check out the Fractal Design XLhttp://www.fractal-design.com/?view=product&category=2&prod=68
They bench really cool and quiet and have a lot of nice features.