Hi
not an expert at these things but i see that a an upgrade to 2.2 Will be available soon.
I am really happy with the phone now Will it make a real difference by updating to 2.2

Probably not.

You may see a speed increase, but you may not. Theoretically the JIT compiler should make things a bit snappier, but my friend (who has a HTC Legend) found that, if anything, it felt slower. Though he didn't exactly benchmark this and God knows how much the Sense UI launcher and Vodafone bloatware made a difference. It's supposed to be nearly 5x faster, but I guess that is only with certain tasks.

App purchases should now sync to the cloud and restore automatically if you do a factory reset.

You might find 1 or 2 apps (at most) require Froyo to run, but I doubt it.

Apart from the JIT compiler, it's a pretty minor update tbh.