MVC is good but I don’t really care if backend is MVC or not as long as my data/content/templates are not.
What I miss in MODx is an (easy) ability to create my own custom content type (like link and document) inheriting from some basic "document" with it’s properties, bindings (document tree/access permissions) and actions (move/publish/hide). TVs+ditto are Ok for a simple site but are hard to extend/maintain for a larger site.
I’m creating a small app with symfony framework and recently found a very young CMS built with symfony – Steer CMS. Looks promising but it’s at v0.1
It requires PHP5 of course (as symfony does), but It’s not a problem to me.