I went over to debian a while ago because it seemed to be easier to get working on my MBP. And it was. Everything installed easily, and specialist packages like pommed that weren't in portage at the time were easy to find. I'm still very impressed with debian, especially etch (though I usually used unstable). It really is a serious distro and is the one I felt most comfortable with moving from gentoo.
However, now MBP support for gentoo has increased loads, so I thought I'd go back and see what things are like. After a couple of traditional compilation errors, I've got a good base system up and running, and have also installed xgl and beryl (far easier than with debian). Also, it does seem to run much faster. We'll see if this is still the case when I've installed openoffice etc and all the things that came with debian, but I'm impressed so far. Strangely, the extra experience I gained using debian has helped me to better understand parts of gentoo, such as init scripts, module loading etc. At present, I'm happy to have them dual booting on my computer
john