Why are you concerned? I imagine many people (and I seriously doubt it's "many") would return it out of principle or spite? Doesn't change YOUR iPad.
My only concern would be if you seriously planned to consume more than 2gigs of data over 3G each month - only you know the answer to that.
I jailbroke my iPhone for the sole purpose internet tethering with my wifi iPad for those time I'm away from wifi (which isn't very often). My data usage jumper from an average of 200 megs a month to almost 800 megs. That's 800 megs for BOTH my iPhone and iPad combined.
But that's me, not you.
My only personal concern is how Steve plans to get us into cloud usage when we have capped data plans. I have Avatar (using a very large file for example I know) on my iMac, my iPhone, my iPad, and my

TV because eventually I'll get around to watching it. If we moved to cloud system I wouldn't have four copies of the same file but just one on the internet I can stream down to the device of my choosing at the time I wanted to watch it. Doesn't work so well if I only have 2 gigs and have to pay a bunch more when I go over.
For what it's worth, I wouldn't worry. Odds are you're in the majority of people that will be saving $5 a month with no other impact.