The shuttle case is actually a barebones system, so it comes with it's own motherboard, so if you hold off but think you might want it later, you'll be replacing both motherboard and case (and PSU). I think the limited expansion room and the fact that many graphics cards take up two slots and need lots of cooling are the main drawbacks of shuttle or other small form factor cases. Some shuttle boards have the graphics slot on the outer edge so you can't put two slot graphics cards in them.