My only real reservation about having access to T3 is the economy. If they have considered it and can keep it reasonable I think there is no difference between staggering the releases to T3 or releasing it all at the beginning. You can count on players being abusive with the economy and if there are safeguards and adjustments to deal with it, it will be great. Either way unlike some other games there are only two ways to get gear either by drops or auction house (no crafting, etc), and all progress is gated by gear score, so there is no alternative method to achieve that.
The other thing this has made me think of is do I feel strongly I HAVE to play support first. Previously, we had time to get up a few characters and have them in the same place to be able to have options to both solo and gear up or switch and support your guildmates better. I’m kind of torn, especially when they say the Guardian content is more difficult so newer players will have a more difficult time with them (I assume), and failing means you don’t get the materials to upgrade and effectively stop progression until you “learn” the mechanics with less room for error.
So, again, kind of torn.