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Yes Open Site Explorer does allow you to compare up to 4 URLs to a given URL of your choosing.

My personal  opinion is not to use Bounce rate as a KPI at all. It's ok to check it from time to time mainly on individual Landing pages but that's about it. Getting obsessed with Bounce rate will only damage your site as you will lose focus on real important aspects. Google takes in consideration, for rankings and when google calculates the "quality score" a different type of bounce rate - not the one in Google Analytics - but only the bounces back in serps and a second click for the same query. Just as a note - I also think the kissmetric formula is wrong but that is pointless since again bouce rate is not really something to be stressed about. Hope it helps !