Having done some additional research, I see reviews mixed -- but more bad than good. Unfortunately, the reviews I have found have all been on the lower-end units.
My only experience was with very brief with a CyberPower 1000Kva tower unit. The unit seemed to function OK and had nice features, but ran VERY hot (e.g. you could not hold you hand on top of it for very long because of the heat). I put an equiv APC unit right next to this one for a new server (i.e. it was in the same environment) and did not experience the same heat dissapation.