As nitro2k01 says, you should always assume that your exit nodes are sniffed. Perhaps it would be useful to configure your network to only direct SSL connections through TOR?
If you're mostly concerned with anonymity, then you might be worried about correlation attacks. The exit node can see all your traffic, and so if it sees you browse to something identifying (gmail.com, for example) and then to something sensitive, it may be able to correlate the two. It's kinda unlikely IMHO but it depends on your threat model.
Reading your question again, though, I wonder - are you planning to run exit nodes, relay nodes, or just the 'normal' use?
If you're planning on relay nodes, they are pretty safe. Bridges are too. Exit nodes open you up to some legal hassles (and you'd be blocked from all services that block tor exit nodes), but I don't think there are any credible security threats from running it properly configured.