I've been running a Sound Devices Mixpre behind mine for a while now and getting some nice results as well(just remember to run some inline pads in front of it since the 184's are unattenuated). I also used to run a MOTU Ultralite mk3 in front of them which sounded good but I think the Mixpre does better on overall depth and complexity.
if interested in some source:
my first show with the Mixpre(I was a little wild in spots, read the notes):
http://www.archive.org/details/nms2009-06-06.flac16.km184same band/same venue 5 months earlier with the MOTU:
http://www.archive.org/details/tnm2008-12-30.flac16.km184I haven't had the pleasure of running a V2 or V3 behind mine yet so I can't give a comparison but I'm sure you couldn't go wrong with either.
Great mics, I love mine, the U89i combo would be interesting. I have had excellent luck mixing km84i's with the 184's in a 4 channel configuration. I would think the U89i's should do well too.
Hope this helps,
J