There are a few characters this is particularly effective with. Vandal Savage from Origin, for example, can potentially heal from his ninth click all the way up to his first this way.

Also take note that the feat has been reworded to say:
"Once at the begining of your turn you can use regen as a free action"

In the old days you could push onto regen and then free action regen. Now you have to wait until the following turn.

You're a little off here.

It has always said at the beginning of the turn.

The errata was to add the "once" because without it, you could just keep giving the free actions until you no longer had Regen showing.