As healer in DF, I'll take the first swift-rez and if the RDM has the next Raise(s) sorted before Swift is back up, it's much appreciated. Think that's a good rule to follow. If you're feeling confident on Raises, you can say something like "I'll take the Raises" or "I'll take the first few", but otherwise Healer -> you is fine.

It always baffles me that co-healers never communicate in DF (even Savage PF) on Raise order. So many wasted swift-raises.