Do you have another $100 (or more) to burn?
In addition to the features we already know about, the iPhone 4G will probably have general improvements to performance and battery, and maybe some other surprises. You're buying a luxury item either way, so it may be worth the extra splurge to buy the best and avoid kicking yourself for two years. Besides, the real sticker-shock comes not from the phone itself, but from wireless providers' mandatory $30 per month data charges.