I tried the B2 national 40deg like 2 months ago with 2 layers of haifu on W968 and I can't say I liked it. It was so slooooow. I didn't even comment about it since I was baffled. I tried probably all the previous B2s and I quite liked them so I am not sure if this needs a faster blade or what. I think I will re-try it on the Sanwei ZLC blade since it's really fast with G09c compared how it was on W968.
Weird, i am playing with the provincial version, and dont have speed issues at all. Unboosted i need to hit a bit harder with my Vsea but still manageable.
Boosted on the other hand it gets fast really quick.
In comparison i found H3 boosted slightly slower. The big difference though is, that H3 has a more dangerous arc. It is way easier to lift backspin with full force and hit deadly loops. It happens that i struggle with it now and then with B2.
Just some input for thought, because i cant compare it with W968, but Gan did it anyway, so i think those blades are comparable to a certain extent.
Anyway we cant say for certain what the issue might be, without seeing you hit some shots