I've used the HOs and did not reckon much to them although someone mentioned today that it is almost a right of passage to own and sell a set and I'd reckon that's fair.
I'd rate Shimano low profile (XTR, XT or LX all perform fairly equally, depends on budget/bling factor desired) highly, have worked well for me with Shimano or Campag aero levers so would have thought they'd be equally fine with Ergo levers. I know that XC Pro (with SE rear) work well with Ergo levers, good power but initially a little fiddly to set up (for a mechanical fool like me) but fine once you know how.
Taking all that waffle into account, I'd have thought that Frogglegs are the No. 1 choice of crossers for a reason and guess but don't know that mud clearance is not the only reason why. I've got a set and am yet to fit but I'll try to report back when I do.
dia compe do a drop-bar v lever
287 springs to mind
I've used these, they do work with careful setting up but do need to be accurately adjusted and, for me, are a compromise and not a very good compromise at that (used them with XT, Deore and Avid Single digit v's).