+1. I went through the same thing when I first upgraded DTV to HD with my HR22, and I set it to 1080i with Native Off at the advice of the guys here, and it works great. No problems and faster channel changing.
You're tv, the 85u (I owned it too), is one that really likes 1080i better. Even OTA sources that were 720p, looked better as 1080i if I let the HDDVR turn the OTA 720p into 1080i, and then send it to the TV.
My new Regza, on the other hand, seems to do very well with 720p, so i think Ill start on Native.