Thanks for the designs, I'm using your Breeder. But here is a reactor design I found, fiddling around, for a Mark I-O EC reactor. It requires 2 reactor chambers, like yours, but must be completely immersed in water (which shouldn't be hard to do). Efficiency 2.33, Output 70 EU/t.
http://www.talonfiremage.pwp.b…=1p10101001501521s1r11r10]
I dunno, I just prefer my reactors to have as much cooling as possible. Frees up room for more efficiency and output!