From what I understand, but i'm not entirely sure, shuttles (i'm talking about the SFF ones) have a special ducting method for the CPU. Does this require the CPU to use the shuttle solution or do you use a HSF of your choice?
You can use other hs/fan configurations, but the Shuttle heat pipe solution works so well I would recomend sticking with that. (Just get an OEM proc. and some A.S.)
In a somewhat related note, anyone own one of these by any chance? how difficult is it to work in such a confined space?
There're quite a few people here who own, or have owned, Shuttle brand SFFs as well as other makes and models. You might try posting in the SFF forum, if you don't get a big response here. To aswer your question, I've never found the space limits to be a problem. They set you up for success with removable trays for the drives, etc...... If you can build a system from scratch, you can easily work in a Shuttle (My opinion).
Probably PUI. Definitely an كافر