kev_rm -
i'm a 4 stroke kind of guy, so you might think i'd reccomend the 4 stroke. i mostly like 4 strokes for their ride-em-hard-and-putem-away-wet nature, but after doing the research for my own bike, it became clear to me that a big-bore 2 stroke is actualy easier to care for than one of the new high-performance, light wieght 4 strokes. so, i went with a '00 380EXC. i can't tell you yet how it will run for me long term, but everyone i've spoken to about is says they are anvils, and since most of my riding is in the woods at low RPM the engine rebuilds wil be few and far between. to a lesser extent, the 300 EXC will be the same way.
anyway, thats my 2 cents.
jeremiah