I was about to buy the Sony P910i last week, but I changed my mind at the last minute and purchase the Treo 600 instead. I would recommend that you take a second look at the Treo and review thousands of applications for it..you will never get that with your P910i..
Another thing, I can tell you that you will find several limitations (as I did) with the P910i. If you are a real hardcore techie, then the P910i will fall short of your expectations.