Mini-itx.com did a review of the EPIA N10000 (note the difference between the N and the NL is the rear connectors). According to them the noise was about 20dBA, so I don't think it's anything to worry about.

I do agree though, that heatsink is huge. I think to get the motherboard, a slimline DVD, and a 2.5" HDD all in a single DIN enclosure you would have to modify the heatsink... a little grinding should do!

BTW, these guys make a pretty cool power supply for the nano-ITX motherboards. But unfortunately they need to make a new design to fit the boards.