I got my iphone like 3 days ago.. Look my advise to you is, just keep your iphone unless you really NEED that extra space... apple (any software/hardware) company will continue to come out with different "newer" products. I don't remember where but a member posted something about apple most likely having iphone 2, 3, 4, 5 generation already but just slowly releasing.
No matter what you have there will always be something newer coming out. Now unless you purcahsed your iphone having to compromise your data because you only have 8 gigs and have like 7 gigs filled up, then maybe it might be a good idea.
For me, i have 3 gigs of music and like 2 gig total of pics/other in my iphone. Actaully more like 2.75 gigs of music and 1.something of pics.. anyway i have 3.22 gigs free. Now do i NEED to have pics on my iphone? NO, i never really show them so no need to have my 4 albums on there. Everything else, (music, contacts, calender,etc..) i do.
On my 30 gig ipod i have the same, 4 gigs filled up and all that additional free. I didn't use.
Anyway be happy with what you have... In 2-3 years when your contract is done, and you really want to buy a new phone, look at what they have (2010-2011).
When i get home i'm goign to be selling my ipod/iskin/car charger on ebay. Can't wait.
PS- What is 3G?