This reminds me of stereo systems. You know the kind with every function in one unit? Well when the CD player goes up in smoke, you send the unit in for repair... guess what? You loose ALL of your music becuase your radio, turntable, tape, etc. was all in that all-in-one unit.
To me it's the same thing with a phone/PDA. I like having my PocketPC as a separate entity and my phone as another entity.
If you're like me, I own stuff until it dies! I don't trade in my PDA or phones for the latest thing. If you are that type, than a combo phone/PDA is an expensive item.