NJ, huh? Check out Pete Minde's site oxygenfedspot.com, and contact him for local advice on skiing in NJ.

Cold new snow is indeed slower, but it should not be that bad. When I lived in NJ I shipped skis for SG by mail to Zach C, or to Nordic Tuning. REI probably mostly does alpine skis which will glide no matter what (with gravity). At any rate, at few days of skiing per year, I am surprised you even bother with stone grinding. Structure does not really matter at cold temps. I use my warm skis for cold temps, just put plenty of Toko blue LF glide wax on them, iron it in a few times, and brush with a firm brush. So either you are not waxing, or the skis are a poor fit flex-wise.