I think it depends more on what percentage of your total time (or more specificly your multi time) it is. If you have 250 hours of multi and 225 of them show safety pilot, then they probably won't take it. However, if you need 500 multi for a job and you have 450 of your own and 50 safety pilot, they wouldn't hold it against you. As far as regionals go, I know some care (Skywest, AE) and some don't.