I have a Revere 6-man Coastal Commander in valise down in the cabin. I decided against a hard top mount because I think it would be way too hard to reach in rough seas, and because the boat has positive floatation, there's no guarantee that the raft would auto-deploy (assuming you get the hydrostatic release).
I'm thinking of replacing my valise with a Viking canister raft mounted vertically on the port-side transom, IF it will fit there without interfering with the motors -- I haven't measured it out yet. That would be an ideal place for a raft because when you actually need it, you might be able to deploy it and then get into it!