I am not sure I understand the question. A text mud is usually a program that uses a parser for input. Alathon has done some work in this area with BMUD and Intermundia. Ebonshadow and Abyssdragon also have parser libs.

I wrote a custom parser for Sana'te which was a lot of work (and continues to be so) but means I have a lot of flexibility in the way I do things.

Well, if you use a lib as a base, you are not really "copying" it. That's what libs are for. You will have to customize it and modify it to suit your project needs, though. I really like the work done with the parsers and ended up using two slightly different parsers in my mud project. It gives considerable flexibility.

I am still fighting some syntax accessibility issues, but that is just par for the course with these things. I think a DIKU style system would be fairly easy to set up with the tools availible in the parser libs. Something more robust and dynamic that allows more complex interactions takes a bit more work. But that's the fun part, right? ;-)

Both! For simple things such as "talk" or "say" or whatever, make a verb. Also, for "special" commands such as "scale tower", "blow up balloon", "cleave taught line", "rig sailboat", etc, make verbs so that the players don't have to guess at the right command usage or use the help command all the time. For more subjective things, like common item manipulation, etc, run it through the parser.

One of BYOND's great default behaviours is that anything that's a verb will automatically be passed to the correct verb procedure, and anything else will be passed to client/command(), which is an easy hook for your parser. Write the verby-type stuff to your verbs, and then write a parser for everything else. There, the best of both worlds!