Well Randy, I totally understand where you are coming from. A lot of shops in town actually charge more to deal with cars with TPMS, because they have to take more care when doing tire changes. I would feel more comfortable taking it to Lexus, but expect them to charge you more for the tires as well.
One alternative would be buying your tires somewhere else and have Lexus do the install. So if they bust the TPMS or whatever else, it's their responsibility to fix that.
By the way, the Bridgestones are awful on snow. I have that on my IS250 AWD, and I am really thinking about getting something else. I was driving to a friend's house, and with not much snow on the ground, I lost control turning left. Heck, I was going only maybe 20 km/h too. I hit the brakes, but it was still sliding forward. Fortunately, I was in a residential area with no cars near. *sigh*