I'm tempted to do the same. But I'd miss the ability to have internet where ever I want using some data plan. Just the savings on being able to price match any time in the middle of the store would be nice. Or the wasted time for the darn store employee to find it on their own website, usually always having trouble.
But my hope for a device like this is to always have it with me. And seeing how I have to have my cell where ever I go, I'd then have these amazing features at my finger tips with an iPhone. If it was a separate device like the iTouch, I'd always be hesitating on taking it with me or not, and often not be with me when I'd really need it.
I think of it like this. You know how you can buy a dvd movie and it goes unopened for years, but the moment it shows up on tv, suddenly you take the time to sit and watch it. Usually this is due to the freedom of watching it on tv, while with a dvd, you have to commit to sitting down for 2 hours if you put it in.
With an iTouch, it would feel like I'd have to commit to doing something with it if I took it with me, say compared to conveniently having all those features built into a cell phone that you always have reason to take with you.