This is just me, but why should classified comments count as 'new posts'? Are your users so hungry to boost their post-count that this is their main gripe?
I do agree that there should be a module for including recent ads on the vbPortal home page... I'm currently looking into a way to hack some of the code that shows the recent ads on the classifieds page to integrate it into the vbPortal page.
I actually think that PP classifieds integrates pretty well... I had it up and running in about 20 minutes... of course this doesn't include configuration time.