Kindle 3 - 3G or just WiFi?

[Godfather]

I'm getting a Kindle. It is settled I spend too much on books, as much as I love having them on paper. The other day I almost bought a 40$ book only available in hard cover... when I saw it on sale on Amazong for 3$

I played with a friend's and some others (Kobo, Sony, etc etc) and the Kindle is the one I like best (Still open to opinion on that though). But I'm now trying to decide if it's worth the extra 50$ + added weight, to get the Kindle with 3G.

It is free 3G service once you have it, but I understand the browser is mostly shit. With that being said, it'd be cool to get the news and other things when away from WiFi

Also... if I have 3G and am constantly in touch with Amazon... are they going to know that I'll be 'borrowing' a good share of books from the web? Is that even a concern?