Well, I've posted my video of the kind the driving I do, and the DWS offers plenty of grip for me. On the last club drive last fall, I was able to pull away from a PS2-clad Z3M Roadster on roads much like that in my video; nobody complained that I was going too slow on my mushy all-seasons
Besides, they DO last longer than summer tires. I got 33k km (20k mi) out of the factory PS2s, and I'm expecting these to go double that at least.
Another advantage: that snow video I posted was last Saturday, temperature was -2C (28F), and I would have been fine if I packed a shovel (easy thing to do in my E90) or the road was less-travelled (stopping on an icy hill is like the worst case scenerio). Today it is sunny and 10C (50F), or warm enough that winter tires will start to get chewed up.
Final advantage: we get a lot of rain here in the Pacific Northwest, and the DWS was able to pull 0.9G on a wet skidpad as tested by TireRack, basically no change from the dry skidpad performance.
Maybe I'm a bad driver or something, but I'll take all the compromises at a price range that is about half of what a set of PS2s would run me. They make these kind of tires for a reason, and that reason is a good reason for me