Thought I would pop the cherry on the MSTS boards with something which has been discussed from time to time at UKTS and TS but seems to defy an answer.
While the chances of me ever going back to MSTS are remote and frankly lessen even further with the passage of time, the biggest handicap is that many of the old utilities no longer install or even work on modern 64 bit computers.
The biggest problem is Demex - the installer is emphatically 16 bit only and no amount of unzipping, copying in Installshield 32 bit launchers has any effect on it. The installer stubbornly refuses to run. Without Demex you are pretty much snookered if you want to make a MSTS route. There was talk on TS a while ago that someone was trying to get permission to redo the installer in 32 bit, but seems to have gone nowhere.
Unless this hurdle can be overcome, those who have upgraded hardware and moved on from MSTS, with no access to a 32 bit machine, have no way of going back even if we wanted to.