Meh, Comp-G's good if you want to do a cam, since you'll have to replace the lower intake manifold (may as well throw in a cam if you're diving down that far). If not, go with an '06+. I've seen a lot of 05's with the aluminum LIM, but heard of quite a few 05's with the nylon gaskets, too, so I'd go 06+ to be sure and just suck it up on the fuel gauge operating backwards (my opinion? Just repaint the gauge backwards).
Reason to get an old one? An extra $5,000 to play with.