I never looked at this as modeling, or even cloning, but more as easy amp modification... I don't change the modules much, but the MTS allowed me to find tones I wanted and create a channel combination that lets me cover three or four channels with less compromise. My RM100 has been configured with the same three modules for a while now.
In other words, it's nice to have a three-channel amp and really like all three channels rather than have one great channel, one so-so channel, and one that rarely gets used.
The only reason I will be selling off my RM4-based rack setup and a few modules is that I don't use the rack rig anymore, and the three channels in the RM100 are plenty, given that I have the tones I really use. Reliability hasn't been an issue (touch wood), but I'll likely buy another RM100 for a backup, and leave it at that.