The T was my first phone. I don't remember it ever being sluggish (for an entry level phone).
The first thing I would do is install a custom launcher, like GoLauncherEx. You will immediately see the difference between the iphone and an Android when you see how customizable Android is in comparison to the I.
(at least I think so. Everybody's iphone homepages look alike, while no 2 Androids look alike).
You'll also notice that there are many more free apps in the Android market (goggle play, now) than the iphone store.
I don't think you'll have any regrets switching over, except to say that the iphone is much higher priced and has higher/faster capacities than your LG does, not being a more expensive high end phone.
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