Hi neutrino !
Nice seing you here
If you want some comparative analysis, you can either check
this (but you must have read it, it is on the marathon thread about txp’s future that Alex, Nils and I launched...) or here @MODx
this thread (you’ll discover Mary is testing MODx too

)
I hope it helps shedding some light about MODx.
In a few words : MODx is a framework, Textpattern is a publishing system. This means MODx allows you more degrees of freedom since you can litterally build an apllication with it (actually the definition of framework @Wikipedia : A content management framework is an application programming interface for creating a customized content management system). This being said, if you look past the current interface of the manager (Etomite’s inheritance), txp and modx share a lot : modular approach, flexibility, light core... great design concepts IMHO. MODx just go one step further.
Wikipedia’s def is a pretty accurate description of the incredible and sometimes mind boggling aspect of MODx

Sencer might call it with sarcasm "the new silver bullet" because I rave on and on about MODx, but I do so for a reason : it might just be the silver bullet app lots of us who don’t know ruby were waiting for