As long as you're not carrying the latest prosumer DSLR with it's manufacturer's name emblazoned on the strap, you're probably pretty safe. Street theives only steal what they can spend, snort, drink, smoke, or sell immediately.
Are camera thieves like bike thieves? Bike thieves come in two types--pros who know what's worth stealing, and amateurs who will take anything not sufficiently locked down. And "anything" means even the most beat POS if they think they can get $20 for it, because a stolen bike is easy to unload. They don't really care about the brand, if it's new, or nice, or anything really. It's mainly about opportunity.