The Django code that comes out of composer2.5, to me, was insulting. Grok definitely was a step up, especially because the fast option reaaally is fast so even if it came out a bit wrong I could just whip it into perfection.
For frontend work, it's a different story. You can still tell that composer2.5 is taking the long route, but I don't think it's as egregious as with Django.
Also, composer2.5 would routinely run commands that were really dangerous and in need of proper sandboxing. Things like creating an ./uninstall.sh script with a HOME variable on which it does rm -rf $HOME. In general, when I asked composer2.5 to do things "for me", I knew a third of the initial commands would be failures, and sometimes they could be catastrophic failures (it did actually run rm -rf $HOME on what would be an actual home folder). This just hasn't happened with Grok.
I also have a bunch of vibe-coded apps I built for myself with composer2.5 and it is extremely noticeable that they hit a "this needs to be refactored as it's crumbling unto itself" line much earlier than with Grok and proper frontier models.