First off, I do not like this throttling stuff... which is why I'm frequently reading these threads to see if anything is changing.
With that said, this debate about throttling at 3GB while having a 5GB/no throttling plan may be misleading. I very highly doubt that someone on the 5GB plan is using 5GB in one or two weeks... more likely gets to 4-5 GB in a billing period. Whereas, the "high volume" users are most probably using 3GB in one or two weeks. So give the 3GB user on "unlimited" plan, and he most probably will not stop at 5GB in a billing period. Said another way, the 3GB user is getting to 3GB much faster than the 5GB user... and so is consdered a "heavy user".
So, as others have posted, the throttling point should probably be 5GB. Then, this "high volume" user has a choice at 5GB within a billing period... pay more, or go slower.
With that said, this debate about throttling at 3GB while having a 5GB/no throttling plan may be misleading. I very highly doubt that someone on the 5GB plan is using 5GB in one or two weeks... more likely gets to 4-5 GB in a billing period. Whereas, the "high volume" users are most probably using 3GB in one or two weeks. So give the 3GB user on "unlimited" plan, and he most probably will not stop at 5GB in a billing period. Said another way, the 3GB user is getting to 3GB much faster than the 5GB user... and so is consdered a "heavy user".
So, as others have posted, the throttling point should probably be 5GB. Then, this "high volume" user has a choice at 5GB within a billing period... pay more, or go slower.