M-Audio Octane or Digimax D8?

Well the pres are in the same range.

The nice thing about the Octane is the phantom is available on the front, but it is 2U and in 4's.

The Presonus is 1U and cheaper, but the phantom buttons are on the back which would bug me. But you also get better meters.

Hmm... I have the Digimax FS which is nice. Pres on the front (love or hate, my setup I like front). Plus you get SMUX for 88/96K and you get D/A which I find handy.

With the Profire if you like the pres on that, the Octane is nice since the sound is the same. So you have consistency. I would probably go Presonus for a different color, but in this range, the "color" is very subtle at best and not in the range of nicer pres. Either will get the job done for sure!