i did a good amount of work on merc/rom based games...but it was lpmud that i really got into!
Yes, I remember those, and played with them a bit. They were a far more flexible, dynamic environment, but 'back then' (in the early 90s), as I recall, the performance hit associated with LP MUDs (inherently dynamic) vs. DIKU MUDs (inherently static) was pretty large, and available memory/CPU cycles were at a premium.
Mostly though I think I preferred DIKU MUDs because I happened to start with them, just by chance.
Good times, thanks for sharing!
Embedded text editor (a modified version of ed), live code reloading, JIT compilation to a VM byte code, translating data automatically between old objects and their new freshly compiled code...