I've driven in snow too. The grip is fine. I just try to avoid days in which there is more than about 2 cm of snow since the road clearance is only 5.5 inches. I'm sure the car could handle 5 cm of snow but the bodywork might be damaged if you hit a big chunk of ice.
Much of the DD versus "garage queen" mentality is in your head. If you commit to using the Elise as a DD you will be fine.
If you read the posts on this site, you get the feelnig that the sport suspension will be much too firm to use for long drives. However, I find that the car is very comfortable in well maintained highways. It is only bumpy in the city, especially if you hit a pothole.
One worry I'd had was that the roofs would leak. In my case each of the roofs works fine. I have not had any leaks.
I have used the car a lot in the rain. I feel better with the winter tires in the rain. The summer tires (AD07) don't have a lot of grooves however it you drive cautiously it is not a problem. If you do have tons of rain you might wish to try the stock tires and later change to something that is better in rain.
I am really enjoying the Elise as a DD. I have snow tires for the winter and I have both of the soft and hard tops.
I drive it about 80% of the time and use an old Tercel the rest of the time. If the Tercel dies I don't think I'll bother with a "backup" car.
So for me the Elise is really a daily driver. I put on about 90 km per day.
There are really only two negatives as a DD.
1) Very little cargo space. The trunk is really tiny.
2) Outdoor parking.
I've got used to 1). If I really need to haul something I have my wife's Mazda 6 I can use.
Regarding point 2), I would not feel comfortable parking the car outdoors for all to see. I would never parallel park it either--too much risk of damage. I am lucky that I have underground parking at my office. So my car is seen daily on the highway but not seen when parked at home or the office.
I want to get a lotus elise and plan to drive it in Vancover where it rains a lot and can get icy in the winter. Since your from Toronto I was wondering how you have found the elise in the winter and as a daily driver?