Mackie Onyx 32 channel 4-Bus vs. 32.8 for summing?

[Bierce85]

Just wondering if anyone could give me some advise on this. I know a lot of stuff has been mixed and summed on 32.8's over the years but I like the portability and preamps in the onyx and also I plan on doing some live recordings.

I ask because I know the Onyx mixers are intended more for live use and the 32.8's are more for mixing and summing, but I don't see why that would make the 32.8's any better if the Onyx is likely a better sounding board with better preamps (I've heard a lot of negativity about the preamps and EQ on the 32.8 mixers).

any thoughts? I'm running Sonar 6 with a Lynx Aurora 16 (16 channels of D/A) and an AES 16 card. I'd like to send some mixes through a decent sounding board to possibly gain a little headroom or warm them up a tad. If it sounds good it sounds good.. if not then it's no biggie. I also need some headphone monitoring.

Bill