Well, I've got a grandpa'd unlimited data plan with HateT&T, and about a week ago (the last in the billing cycle for the month), I hit the 3GB throttling threshold. Determined to basically show them I'm committed to using the service for which I'm paying and have paid for years as a loyal customer, I proceeded to use the 'ell outta my phone for the rest of the remaining cycle time. Turns out, at least in my experience, the throttling wasn't so bad that it drove me crazy having to wait on things. I still was able to load web pages in a decent timeframe, and was even able to stream Pandora for about 90 minutes with no pauses, stutters, etc. YMMV of course. But with that realization, I'm not too concerned with the throttle so much that I'm looking elsewhere for a new plan/provider, or looking to reduce my internet usage. Sometimes Wi-fi ain't available, and when it's not I won't be panicking.
Just thought I'd contribute something to the conversation, since I think someone on Page 1 inquired about the throttling experience.