I think you have it now! As a veteran of 30+ years of mountain snowskiing vacations and also living in the snowbelt I like dedicated snow/ice tires. But I have also had several successful mountain vacations with good all season tires!
The realities are:
In a blizzard many passes will be closed, they will not let you go and get stuck up there. Be prepared to go back and stay someplace else that day!
The chain law may often be on, and they accept cable chains. They sell cable chains EVERYPLACE in the mountains, even some supermarkets in Colorado stock them. IF a pass was open to 4WD vehicles with chains only, I would not go anyway.
A Colorado Highway patrol study said clearly that your risk of getting stuck is modest compared to going off the road and flipping, especially for high C.G. Vehicles.
You may spend the entire winter mountain vacation looking at beautiful snow covered mountains, parks and ski areas, while driving on dry roads!!
Go, have fun, enjoy the beautiful drive over the passes as opposed to trying to set a speed record and passing everybody in sight! Then, next year after you get addicted to winter mountain vacations (maybe skiing) buy some snow/ice tires!
fsskier