Exactly the reason why it wouldn’t be the brokers which would have ratings, but the reviews themselves.
Lost yet? 
It’s like this. You Tess land at the first page of the site and you see a list of brokers along with option buttons beside each to go to their review or go to their thread on the forum (not babypips forum, but a forum* there at the review site).
The brokers are listed let’s say alphabetically, or just simply in the order that they came into the site. There would not be a rating next to each broker.
You click on the review button next to the broker and you are taken to the page of reviews. When reviews are submitted the author will have to answer questions such as how long they’ve been trading (and how long did they demo trade before they began trading live), how long were they with that broker and how much money did they put there, etc. Then the author can give specific comments (or not) about their experience with the broker.
The review gets posted (after being edited by admin for foul language or slurs, etc.) and the readers rate the review on how useful it is!
*Why a forum, you ask? I think it’s a really good way to get to know people, both the authors of the reviews as well as the brokers/brokers reps. It’s a way you can cross check your information (and we all know in Forex that you have to cross check everything ;)) If babypips partnered with me to do this, the members forum name here would be their name at the review site, both for the reviews and the forum. If babypips doesn’t partner with me then I could partner with another site.
Anyway, just still kicking the idea around. It’s no easy task.