+1 to that. If the IMS issue scares you a lot, either (1) get a car that's had the retrofit done, (2) set aside a couple grand to get the retrofit or (3) maybe a 996 isn't for you. Not really sure if it's a common enough issue that you can use it to beat the seller down on price. There really is no consensus on what causes the IMS issue, but gently-used garage queens with low miles for their age seem to be more susceptible--probably because they don't get their oil changed often enough.
Crankshaft problems are a new one on me. As for cab tops, my 02 doesn't leak a bit, although it only gets wet when I wash it--it's strictly a dry day car for me. If you want a cab, I'd stick to 02 or later, because they have the glass rear window (among many other improvements). All Porsche rear seats are going to be tight, but cabs are probably worse, except for the unlimited headroom.
