Thanks! I’m also socal but make frequent trips to the mountains and want a single wheel/tire setup that will perform decently in snow without sacrificing too much in terms of handling/performance everywhere else. Not sure how the (relatively) narrow tires would feel on the Performance.
Are you comparing performance/handling between the stock staggered setup to a squared A/S setup, or are you comparing a squared summer setup to a squared A/S setup? I ask, because you are changing two attributes at the same time.
Comparing squared to squared, the only difference I think you'll notice is at the limit dry handling. That's how I felt on my other car, when I switched the staggered Pilot Sport Summers to a staggered Pilot Sport A/S. Dry handling was very good, but not quite as good as the summers. However I felt the wet handling was near identical... This was reflected in pretty much every review I've seen as well. In the case of the DWS 06-Plus, I saw the tirerack review, when you look at their charts and read their reviews, the DWS 06 Plus, exceeded the Pilot Sport A/S 4 in both dry and wet handling, so should translate into an even smaller gap in performance discrepancy between your summer and a/s setup...
The main factor you can't get around, is if you are comparing the staggered setup to a squared setup... I'm not sure how prone the Y is to rotate the back, as I've never taken mine to the limits yet... But if my Infiniti is any indicator, it's easier to rotate the back around when running on a squared setup then a staggered setup.
On a side note, on my commute this morning, I was pondering tires, and I realized something. Unlike other cars with a staggered setup, the Tesla uses the rear tires for regen braking, which means if you one pedal drive most of the time, the rears will probably wear faster than other RWD biased cars. Which means on a staggered setup, you'd go thru tires faster than other RWD staggered cars.
For me, personally, I got sick of the hassles associated with a staggered setup, which is why on my next car, I decided to go for a squared setup.