Better to put the changes in now and see how they affect the gameplay rather than putting everything in all at once. Think of it as testing, especially considering it is going on the PTR.

2-3 months on PTR then 3.3 comes out.

That puts us around end of year.

You really think they are going to leave the end of LK on there for more than 6 months?

I think cataclysm is going to show up a lot earlier than some folks anticipated.
Putting these changes in now allow people to get those alts up to snuff and allows people to level up a character faster. This is one of the few things end game raiders can do once they have gotten to see all the content.

See all the content again, only without the tedium of taking so long to go around places, drink every pull and essentially be a wimp for 19 levels.

Honestly, I'd say 1-2 months on the PTR. They're going to want a big new content push out for the holidays. Drive sales and get people home from the holidays to reactivate their account.

I think these mana/health regen changes are to fix what they broke with the spirit nerf a couple patches ago. That was a necessary nerf for level 80s, but it made leveling, especially at the very low end, much more painful for casters.

Why not just start characters off at level 58?