By "OEM Pirelli's" it sounds like you are talking about the ones that come on the 22" wheels which are the base variant where the literature says they can drive in light snow, but the tire doesn't have an M+S rating and the words all season don't appear on the tire in the pictures I've seen. They'll be out-performed by the A/S and the A/S Plus variants in snow. Tirerack does list both the OEM base variant and the A/S Plus variant for that car and the ratings on the A/S Plus are way better than the OEM variant (and similar to the DWS, but the DWS has more reviews so I'd trust its ratings more).The DWS06 is significantly better in the snow than the OEM Pirelli's. The caveat is - as long as the S still shows. The treat has D W S stamped in them - Dry, Wet, Snow. Once the S disappears, they're crap in the snow as the top compound has worn.
So, yes, on 22" wheels I would steer away from the OEM tire towards the DWS, but the Pirelli Scorpion A/S Plus is a possible alternative, especially if its good ratings hold up as more customers report in.
Tesla also uses Pirelli tires on their (19/20") winter packages, and those could also be called OEM, but those are dedicated snow tires (Pirelli Scorpion Winter) which are in a different class and would outperform all of the others due to being designed specifically for snow and ice. I was assuming that nobody here is talking about those wheels/tires...