You have to shift your weight more to maintain traction on climbs on a hardtail, IMO. Practice makes perfect.
As well, I'm betting your OOSS is slacker angled than the GT - that can make things tough when still adapting. Takes a bit more front weight to keep the front end from wandering.
Then you have to keep moving around on the techy stuff to keep the rear from breaking free...
It's a balancing act. Keep at it, and you'll get it! Did you swap to different tires as well?
As well, I'm betting your OOSS is slacker angled than the GT - that can make things tough when still adapting. Takes a bit more front weight to keep the front end from wandering.
Then you have to keep moving around on the techy stuff to keep the rear from breaking free...
It's a balancing act. Keep at it, and you'll get it! Did you swap to different tires as well?