Arguments in favor of extending Dave's ETP Wiki:
-  Already uses CR. To extend the current Wiki code, I'd have to learn a lot about the CR the hard way.
 -  I like that it doesn't take HTML code. Seems like security is handled better.
 -  I could learn about ETP and CR in an easier way.
 
Arguments in favor of extending the current Wiki code:
-  Has automatic link generation (critical for Wikis). I would have to add this to ETP Wiki.
 -  Path of least resistance -- it's much easier for me to fix and extend this code, because it involves what I already know how to do (adding in permissions and templates and so on).
 -  Right now, I think the interface is better and easier to use than ETP.
 -  ETP is going to be rewritten, so I don't have to worry about rewriting anything sitting on top of it. 
 
Honestly, the second approach seems like less work. I'm open to arguments for doing it with ETP, though. 
I also haven't looked at Dave's code yet, so maybe I'll change my mind after I do.