My friend and I are planning on building a sort of a forum type of webapp.
We've used the major PHP frameworks but we're really thinking about using Python specifically the Pylons framework for our app. Although we're competent PHP programmers, we're somewhat noobs at Python (We could create practical scripts and such). But the thing is we really want to learn Python but by testing Pylons out it seems to be really difficult with all the numerous imports and all.
What would you suggest? What advice could you give to us? How would you suggest that we learn Pylons?
Decide what you want to put your focus on, being productive or learning a new language:

If you want to learn Pylons and Python, use Pylon and Python.  
If you want to deliver a stable forum software, use PHP, because that's what you're competent at.  

Note: I should add that this is not meant to imply that you cannot be productive with Python or Pylon in general. All I'm saying is, in your case, you will be more productive with PHP, because you know it.
Should we use Pylons or PHP for our webapp?