I've built a shuttle and I've built a silverstone box with a mATX both with
all the goodies and I would never buy another Shuttle. The options you get
with other boxes make the difference.
The shuttle I built 3 years ago has had a power supply go out(high $ and
took 10 days to get), and now the motherboard video bus on the motherboard
is bad and I have to scrap the whole barebone system. Looks great but a
bunch of junk.
If you want a nice small form factor machine, buy a small box and off the
shelf components.
Just my thoughts and experience. I could be wrong but I don't think so.