Slant the ceiling or not???

I am building a two roomed studio, 12x15 and 8x15, the height then, I'm not too sure. I was planning on having a straight horizontal ceiling, but then I was reading a tutorial from realtraps modecalc from ethan winer, which says "a vaulted ceiling is desirable." So then I was thinking, I was going to go with 8' high ceiling for conveinience, eg sheets of drywall fitting flush and the other pro's, BUT that would mean in the control room having 2 dimensions the same! So if I went with a slanted ceiling, 8" to 10", it ould mean no dimensions the same, cuts out the axial mode between the ceiling and floor (I think, in my head it should just from general knowledge, as it won't go back in the same line...right???) And if i put my drum kit under the 10' high part, it would give more height above, even though its slanted that would still be better wouldn't it? So......Is it better, is it worth it, are my reasons valuable. if i do put it slanted should I put my moniters going towards the 8' high wall? Making me and my gear at and facing the 10' high wall! Here is a little plan to show you what I mean!

use the higher part as your back-wall