PR does not bring traffic, the position in the SERPS does that. A low PR site on a niche topic will happily sit at the top of the SERPS for key searches. A high PR site will still do badly if it does not contain the terms that your customers are searching on.
I have no idea what the PR of my main site is. I have built it to be in the right place in the SERPS and that is all that matters to me.