Closed-Loop H20 System Question

[Neptune]

The system i have right now currently uses a resevoir which works out well because it's in a large case. I plan on building a second box with some extra parts i have around but the case I have is fairly small. At first I thought about just buying a larger case, but then i considered just running a closed loop system, eliminating the space need for a resevoir. A small in-line pump could easily push the water around.
Are there any advantages or disadvantages to running a setup like this? Also, if someone could shead a little light on adding a bleeding/expansion hose it would be appreciated.

Thanx in advance!

[Badger]

I run my watercooling closed loop with no tank. I put a tee piece near the high point which I use as a fill/vent point, I have a short hose on the tee which I leave only part full to allow for any expansion. Works fine, filling and venting takes a little care but you should not need to do it too often.
See the pic: