It's good practice to discuss plans with your hosting provider, so that you and they both know what to expect. Stealth doesn't cut it, especially if there's real money at risk.
Also, keep in mind that relay IPs, and perhaps even subnets, may show up on various blacklists. Other services (perhaps those of other hosting customers) may be affected.
I recall seeing this on tor-talk or tor-relays within the past year or so. Someone started running an exit, and their hosting provider nuked their account, claiming that other customers were being affected by bans. I'll see if I can find it.
Edit: Here's one example, posted by Zack Weinberg on the tor-relays list.[0]
CMU network operations has decided to move the Tor exit node that my
group operates (tor-exit.cylab.cmu.edu) to an isolated subnet in order
to minimize consequences for the rest of the campus network. For
instance, apparently there have been several cases where third parties
blacklisted the entire CMU IP space in response to malicious traffic
from the exit node. This is currently scheduled to happen Tuesday (Nov.
4). The new IP address will be 204.194.29.4.
It is quite expected if you run an exit node. However this was in regard to a relay node, which is something else entirely.
I've seen a few references to these supposed problems with running a relay nodes lately, but the poster never replies with any information where this have actually happened. This behaviour is new. It wouldn't surprise me if it's coordinated, considering what else we've seen lately.
It happened to me when I ran a tor relay (not an exit) on the same ip as a mailserver. There is one rbl that automatically adds you if you do this. Mind you, I've never found a mailprovider using this list (can't remember the name).
Also, keep in mind that relay IPs, and perhaps even subnets, may show up on various blacklists. Other services (perhaps those of other hosting customers) may be affected.