Since there are 2 developers working in punbb.net that are not working on punbb.org, there is the loss for punbb I think. Why have 2 teams while could have one bigger more powerfull team?
Also, punbb 1.3 took so long to launch, and now I don't see a punbb 1.3.3 until maybe the end of 2009. I will rather see more mod finished and maybe an upgrade routine that does not truncate all of your 1.2 forum text in your DB(migration to UTF-8 is broken and should not ship).
Of course there is place for all programing languages, but maintaing 2 code base is like shipping a forum with custom implementation of php5 in php4, a lost of time in my view. "Reuse as much as you can" should be the idea.
Good luck and let see how this evolves