"... so, I thought, why not?"

I needed to cut the vent holes large enough to make the case fan screws accessible; but, I wanted to keep them as small as possible -- at this point, I still wasn't sure how I'd affix the filters.
 
By this stage, I'd reversed the motherboard tray in the right hand server. Cooler Master did a very good job with the symmetry of these cases, though alignment wasn't perfect. In the end, I left one of the roughly 15 screws out.
 
Also note the "decorative" curved platic on the top of the case. It can't be removed without exposing metal edges and it needlessly adds about half an inch to the height of the case, though I suppose you need some clearance if you're going to use the "blowhole" fans.
 
At this point, I think I probably should have left the 80mm fans out of the top, and covered it with sound-proofing material. CM's proprietary mounting bracket for the fan would make it a bit more awkward to do that and not degrade the appearance.
 
I have considered mounting another peice of wood to the top... I could use the thickness I'd save by removing the plastic garnish, I'd cover the blow-holes, and the whole cabinet would have a solid top to work with. Of course, having only three wheels, usage as an end-table would not be recommended. If I were going to have it in an exposed location, though, I probably would've stuck with 4 wheels with the side-removable filter setup.