I'm a recent buyer also. I replaced a Mesa triple Rec with a RM100KH with the 3 KH mods and a plexi and an Ultra XL. Very cool amp so far. I've owned just about everything in the way of high (and low) end high gain and this amp actually holds its own very well. I've had 6 Diezels (Herberts and VH4s) 3 or 4 Uberschalls, Egnaters (MOD100, MOD50)Elmwoods, Framus Cobra, VHT UL, all the way down to the lowly 5150. I really wanted to see how this sounds compared to the Egnater version. Suprisingly, there's only maybe a 5-10% difference in the sound to my ears (not that one is better or worse, just different). The egnater sounds a little more vintage to me. The RM sounds a little more modern (snobby fellas will say its more sterile and less organic). I think it holds its own. Then again, I could probably buy 3 Egnaters and they'd all sound slightly different too...
The KH2 and KH3 sound a lot like a VHT to me. Very clear and dry, but mean as all get out. When you turn the gain high on the KH3, it saturates better than an Ultralead does and really comes into its own. KH2 is cool, but I find myself not using it as much. KH1 is a nice clean. I use it with EMG 85 and it stays nice and clean. The plexi I have no real use for as I don't play much stuff that requires that type of gain (plus I can turn the KH2 gain down and get something that works for me when I do). The Ultra XL kicks butt. Very nice mid rich high gain tone that just soars. Very cool module. Have a hard time deciding if I like the KH3 or the Ultra XL better.
Still want to try a 1086 myself.