I'm starting to think that eating sranc won't be a big deal. I think Kellhus would have tested it thouroughly with all his trackers and outposts, like at Fatwall. Of course he couldn't have tested what would happen if Mog awakes. Perhaps a steady sranc diet leads to moderate increases in lust and violence but no more.
Also, I gotta think that the Stone Hags or any company that was out too long would have eaten sranc. So whatever the effects, its not so crazy that they aren't too unlike the Stone Hags we meet.