Just blew a few hours with an over compressed preset recording an acoustic guitar with a couple of mics.
Anyone had good results with presets on this unit?
 I assume I'll have to modify one of them.

Bring it in clean. Monitor however you want, but record it clean. Edit non-destructively after the fact, and if you need to destructively edit, clone the track first.
 
If you absolutely positively have to process on the way in, and I do sometimes, I never trust any kind of monitoring except the two step process, test record first, then playback to see how it sounds. Your monitor chain might be truthful, but 'might' may end up in your pocket if playback doesn't match.

I have tweaked a couple of presets to eliminate all but light compression/limiting but if I don't use a preset at all (off) I don't get the levels I need.
I am getting noise tho, so a noise suppressor is often needed in there.
This has its problems too.
I'm hoping it's just that I don't know the right settings rather than the BR 800 is not up to the job.