I live in SW Portland and have had my ST for almost 3 years. In that time, it has always had summer tires. I have had the RE050A's, the Sport Comp 2's, and the Indy 500's now. I have never had a problem with cold weather on any of those tires, and I drive my car every day, rain or shine (mostly rain here). In the last three years there are a grand total of probably 5-7 days where my tires would've been unacceptable, and during those conditions all-season tires would've been inadequate as well (Ice). In that instance, if I HAD to go somewhere, I was able to take my 99 Blazer with Blizzaks and had no problem.
I think the "summer tires don't work in the cold" is completely over-blown, especially in the PNW. Yes, in below freezing weather in other parts of the country, they wouldn't necessarily be my first choice. But here in the PNW, 99% of the time in the winter, it is 45 degrees and raining, and summer tires are perfectly fine.
If I didn't have an SUV, couldn't work from home, and didn't have access to public transit, I would invest in some Blizzaks, which are available in our stock size and are fantastic. You will save your summer tires in the winter and you get the benefit of summer tires in the summer, rather than compromised all-seasons. They are called no-seasons for a reason.