If anyone is interested, I'd like to comment on my experience and opinions. I had 3 rm100's (one 2x12 and two heads) and two seperate KH's at one time, as well as my step-dad having a rm50 (which I can hear the difference in but that's another story.). In my humble opinion, the KH is MUCH different than the rm100. The KH was overall much darker and smoother in tone and has more low bass that shakes the ground, like a H&K Warp T (now known as warp-x). I couldn't get the two to sound the same at all. All of the modules were much darker in the KH with a velvety feel and a thunderous low end. I ended up returning the KH models, only thinking of keeping one because maybe it would offset the lack of sub lows when adding a MM OT. I ended up not giving that a try though and ended up sticking with the RM100 because you can hear the harmonics better and It has better mids, even for a "metal guy". I'm really picky and am one of those guys that can tell the difference cables make etc., however, I don't think you'd have to be an audiophile tell the difference. For me, the difference was very pronounced and I can't imagine getting the same sounds with the two amps. That being said, most modules are made to sound best in the rm100 and, to me, most sounded best in a stock RM100 because that is what they are tuned in (Probably why I didn't like the MM OT). As a side note, the KH is a cool amp that gives the mods a deep dark flavor that many people might like. Some mods sounded cooler in the KH, especially the KH preamps. It brought something else out in them.
That's my opinion.
-Angel