Hey Chad,
I just rented a BMC Fourstroke 03 this past weekend at Tsali and can offer some impressions of how it rode, etc.
First of all, the bike seemed to be solidly built, with clean welds, smooth matte black paint, and a stiff rear end (no flex). The particular bike I rode weighed about 28.5 pounds and was equipped with some fairly heavy components: LX integrated cranks, SRAM X9 Drivetrain w/X-Gen F.D., Rockshox Reba SL fork, FSA stem/bar/seatpost, and Cane Creek Terros wheels.
On the downhills, the bike felt rock solid and super stable. You didn't have to worry much about picking the right line as the bike would just float over rocks and roots. Very confidence inspiring. Also, in rooty sections, the bike felt like it tracked very well, and I was able to stay in the saddle the majority of the time. On the uphills though, the weight of the bike seemed to hold it back and it just didn't accelerate as quickly as my friend's 24 lb Stumpjumper. The rear end felt very efficient, however, and hardly bobbed even when I got out of the saddle.
The bike steered quickly enough, and was easily able to handle tight woods. Not too fast or slow. Personally, I prefer really snappy handling and an aggressive position, so the bike felt slightly more upright and laid back than I was used to. It felt like it was better suited to a 12/24 hr race than a quick 20 mile race (or cross country/trail riding rather than racing).
Anyways, I thought that it was a great bike and could hold its own against what other mainstream American bike manufacturers has to offer. If you have any particular questions, I'd be glad to answer them.
David