I know I'm late to the discussion but I've been using nothing but sourced based distros on my intel 180 GB ssd asus laptop for about 2 and a half years now and no compiling in ram. I still get the same read/write speeds as when I first installed and regurlary do emerge -e world, so I don't think its quite as bad as everyone thinks, also have a ssd gentoo server which I don't update as often but haven't had any problems on it either. The only thing I botherd to do was switch my scheduler to noop and added noatime to my fstab.