I had Blizzaks ws70 on my winter rims through last winter, and had no problems with tire wearing. I'm from NE (Connecticut), where it snows and there are periods of time when we drive on dry pavement. As long as you don't rapidly accelerate/brake and don't go over 65 mph, you are going to be fine. I'm driving mainly on the highway (mostly dry surface), and sometimes side roads. My tires should last me two more seasons.
PS: Get Blizzaks ws70. I had no issues driving 2003 Nissan Altima during snowstorms. It's going to be even better with your Subie.