I've never used Mac OS X Server so can't comment on its worth, however... based on the hardware specs and the prices, I can't work out how they ever sold a single one (except to huge lovers of Apple who wanted to look geeky and hip at the same time by having one of these in their home.)

edit: If the price was only a bit higher than what I'd expect to pay for those specs with 5-10tb storage in it, then I'd probably be ok buying it as a home storage device, much the same as I'm ok buying an iPod as an MP3 player. But there's a point where "sexiness markup" becomes "double the price and slap on a bit more".