Thanks for your comment Luis. :)
It would be nice if I could apply certain labels across all workspaces — in fact, if that were the case, my GTD method within might look a bit different (or, at the least, there would have been less redundant labeling in certain workspaces). For the current iteration of Producteev, though, the set up I describe above is working really well for me! Producteev is not designed for GTD, but you can make it work with a bit of creativity.
As for Toodledo, Evan (also from 40Tech) uses it and likes it quite well, and I agree it is a very powerful tool. I couldn’t get into it, though. Something about the interface bugs me — I can’t quite put my finger on it, but it doesn’t inspire me to want to keep looking at it, and that is death for me with To Do software.
I like the flow of Producteev’s look and feel, and its ability to integrate fully into tools I already use. The only thing missing for me was a solid GTD implementation — and now I have that. I’m always looking to try other methods (it’s practically a compulsion :P ), though, so I may get back to Toodledo at some point.