Thats a hard question, since there are so many sites with different information in them, but if you give me a few months i think i might be getting close. Havent imported a whole lot of information yet but plan to very much so in the future.
Currently my site sits at approx 15 - 20,000 content items with not that many reviews. Thats the good thing about jReviews, with the CSV import tool it is very easy to import alot of items, just alot harder to get them reviewed lol!
In terms of larger sites, i havent' pushed the limits yet, but it seams to work well as is. If you turn off counts in the sections and categories you will notice better performance.
There are quite a few sites you will notice, there is a techdb which has abit, travel shop ireland has alot to. My site is reviewyou.com.au, if you browse to Food & Drink i think, then Dining you will notice alot, or Entertainment, Magazines. But visit back again within the month i estimate and you will see a site that tests the boundries of jReviews and Joomla
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Hope that helps, interesting question though....
