Actually that depends on how the actual blog commenting is done.
What I'm considering is filtering out the high PR's ones, and outsourcing commenting locally to a native danish speaker, to improve stick rate.
Low PR's could be blasted and outsourced here if I supply a spinnable comment.
To that end, the more url's the happier. Otherwise if commenting is strictly manual, that put's a natural limit on how many I'll need for now.
