If I may also be so bold as to suggest…
Can we score products based on multiple criteria? Rather than a simple 5 star review structure, perhaps something similar to the “Ebay” way, where you give a rating out of 5 stars for (in our case):
Product Quality
Support Quality
Update Quality
The Product quality can be tied only to the product, and the Support/Update quality can be tied to the seller account, therefore allowing people to gauge the support/update support from the seller regardless of which product of theirs you’re currently considering.