Just curious - knowing what you know now, would you buy the working firestation combo for $1300, rather than slog through your own setup to save $300?
From where I'm looking the difference might well be worth it for a lot of folks - but then a lot of us actually "enjoy" the tinkering.
If you're a system tweaker, who likes to putz around with systems, certainly building your own is going to provide much more bang for buck...
However, it's been my experience recently, that some of these high-end systems require some tweaking to ensure they're stable under stress...and LinuxMCE will put some stress on a MD machine...especially with HD output. The upside to dealing with a system like the fiire, is that they've done the testing and tweaking to ensure stability already....when WAF (Wife acceptance factor) is critical, stability is of primary concern.
That's largely the reason i'm using the dell systems....same deal....tuned and tweaked already for stability....if I didn't have them on the shelf, I likely would be looking very seriously at the fiire systems.
On the tweaking front...I've seen some AMD motherboards where, depending on the CPU and Memory brand, you have to adjust voltages on the memory sticks to get them to perform reliably (and that's not overclocking...just plain old stability)....
So if you're the type who likes to tweak and figure out if it's hardware or software that's failing...and we need those types to populate the wiki with system configurations that are tested!...then build your own system and save $300.00....if not, then it's likely worth the slight price premium for a solid out-of-box experience....