I think they are sitting in slightly different pieces of the market. I'm far from a design expert, but everything I see on Dribble seems like finished work (or at least polished and ready to show off). Often on Forrst I'll see stuff that people are struggling with and requesting real feedback on.
As someone who is about 95% developer and 5% designer I'm well aware that there is no place for me on Dribble, but Forrst users are happy to critique and offer solid suggestions on how to improve my limited design skills (which is something I'm really grateful for).
As someone who is about 95% developer and 5% designer I'm well aware that there is no place for me on Dribble, but Forrst users are happy to critique and offer solid suggestions on how to improve my limited design skills (which is something I'm really grateful for).