SEO - Product Reviews Question

I wanted to get an opinion from some of the successful amazon product marketers (and/or other affiliate marketers). I have an authority site with a PR4 in the green home market (not diy solar) with my main keyword "green homes" on page 1 of google. The main site is primarily articles about building green homes, energy efficiency, healthy homes, etc.

I want to start writing product reviews and targeting amazon (or other affiliate networks), so I understand targeting a set of products / keyword research / etc.

My question is would it make sense to use the wordpress multi use function and thus all of my product related blogs would be in the sub directory. I can link to these blogs from my main site - would this make sense? Would this build up my site in to a bigger authority site. Make my product reviews more relevant to google as part of a large site, yet still able to do seo/backlink to the targeted product blog. This seems to make sense vs building brand new stand alone sites.

My structure would be (i think ):

productcatergory1blog.mainsite.com
productcatergory1blog.mainsite.com/product1review
productcatergory1blog.mainsite.com/product2review

Thanks.