I had an Ardent with an HRII on the front for a while (not by choice, just came on a bike I bought secondhand). Seemed to work well.I've got to say I do prefer an Ardent on the rear to the Aggressor I'm running at the moment.
Corners just as well, just as fast, but more grip in a straight line, stopping and going.
I've only tried one Aggressor size (a 26" in 2.3) but didn't rate it. Didn't seem to stand out in any way, and in the wet it was hopeless.