I have two and they are in year 2.5. Doing about the same as yours. I'd compare them most to a lacecap version of Incrediball. Here was mine last year:

Yours look great! I hope mine has that many blooms this year. What H x W did yours get? If I remember right the tag said 5' but that's probably for a warmer zone. Also do you think it is as prolific of a bloomer as Incrediball?

They'll easily get to 5' if you leave at least 2' of stem left over from Winter. Most H arborescens should bloom about the same given good growing conditions.

IME on the edge between zones 4 and 5, H. arborescens such as Haas Halo won't die back. They are far hardier than the typical Hydrangea macrophylla (pink/blue flowers) and in zone 6 you should have no die back at all and will grow to the size indicated on the tag.

The only "dieback" you should get on H arborescens are that a handful of stems will dry out and die off naturally each season. You can find these immediately after it starts to leaf out and get rid of them.