I've seen claims in both directions. To play it safe, I'll keep my 3G on 3.x. There was only 1 new feature in iOS 4 (that also worked on 3G models) that attracted me anyway: the unified mailbox view thing. Actually I have a short list of desired improvements that might make it worth it, despite a speed drop: * photo synching to my desktop (so not limited to the lame select-up-to-4-then-email-them thing, which is way…
This behavior is extremely frustrating. It is similarly annoying when Safari reloads a page because the previous copy has been reclaimed due to low RAM. Rather than flushing the previous version entirely, it would be much nicer for Safari to write the old version to flash. Reloading from flash would be much faster, and would also prevent the page content from changing on reload (e.g., Google Reader won't reload "read" items on reload).