The thought came to me a while ago, that all of the life raft survival stories that I have read (and I think I have read them all) take place in warm waters. Yet I sail in the Pacific Northwest where the waters are very very cold. So why are there no cold water raft-survival stores? Hmmm....
I think we have found the answer to your prior question about anxiety. STOP READING SURVIVAL STORIES!
I'm just a bit South of you in the Tacoma area. The only time I would worry about it is when you are going to cross the Straits. The rest of the time, as long as you have a VHF and wear a PFD, you can go overboard and your chances of survival are excellent.
A typical example, we were returning from a cruise and coming back home. We heard a call on Channel 16 about a power boat which had caught fire. We dropped sails and started motoring over to that location, about 2 miles away. By the time we got anywhere near the scene, there were four other boats on location assisting and Vessel Assist was only minutes away. There are very few places in Puget Sound where a VHF radio call won't get you help in a very, very short period of time.
So, if you have a life raft, staying warm won't be the problem, just keeping from being run over by all the yachts coming to your aid will be the problem.
Of course, once you are North of Admiralty Inlet, it is a different story. Even so, I don't have a life raft and don't plan on getting one, my dinghy is fine for this area. However, if you plan on heading out beyond the Swiftsure light, then a life raft might be a good idea.
As for survivability of the water. Puget Sound has a seasonal water temperature variation of less than 10 degrees F. In the Winter, with water temps in the mid 40s, a typical person in a PFD can last about 2 hours and in the mid 50s Summer temperatures, according to the US Navy. Of course, while you may be alive after and hour in 50 degree water, you won't be much use as far as swimming or pulling yourself on board a boat.
Anyway, given the relatively crowded waters of the Puget Sound, the rapid response by fellow boaters, LEOs, USCG, and Vessel Assist to any distress calls, your time in the water will be relatively brief.