It's very possible that the blue who said "60-70 will take as long as 1-60" was just misinformed. It's not like blues have never said stuff that wasn't true due to them not knowing any better :-P

Regardless, the point at hand is that they are not going to allow alpha and beta players to stay level 70 into release. You'll have to start over with everyone else, and it would be unfair any other way(You already have enough of an advantage just by having PLAYED from 60-70, much like someone who has leveled 1-60 can level to 60 a lot faster than someone who has not.) You know the quests ahead of time, any nifty tricks to deal with certain things or situations, you've got practice with any new spells/talents that everyone else will be adjusting to.