I said farewell to Shuttle for a while and built a new system based on Intel's H57 based DH57JG motherboard and Silverstone Sugo SG-06 chassis.
DH57JG doesn't offer any real "performance" features, but still has a rather nice feature list and the Intel boards have usually been pretty stable. SG-06 is not the smallest chassis available, but if offeres possibilities for later expansion, if needed (e.g. a separate graphics card).
SG-06 next to SP35P2. SG-06 is about 4 cm shorter than Shuttle P2 both regarding height and depth. Width is about the same.
The chassis and motherboard would allow even for a double-wide graphics card, but currently I am trying to see if I can live with the built-in CPU graphics in i5-660 (as I do not game). There is the slim DVD drive on top and the 2.5" HDD attached to the bottom of the DVD cradle.
In the inside I have got plenty of room, as using a 2.5" HDD enabled me to remove 3.5" HDD cradle completely, which leaves the fan pretty open and enables good airflow. I changed the default 3-pin fan to a 4-pin PWM fan, but otherwise no mods.
The left side of the SG-06 has a rather large vent, which helps with a large video card, but might cause trouble when there is no card. I tackled that risk by covering 3/4 of the large vent on the left with a black plastic sheet taped inside the chassis cover. That prevents air escaping too early and forces it to go towards back of the chassis.
Cable management is not finalized, although they can be tucked away pretty nicely already now. Shorter SATA cables would make life easier.