well, i never used sequential shifter IRL, but in LFS, sequential shifter and automatic clutch is way too FAST compare to what you can do with H-Shifter + automatic clutch .
So when you chosse H-Shifter, you can only be SLOWER than autoclutch + seq shifter.
That's a shame, with H-Shifter you take risks to miss a gear, AND you shift slower ... you got the pain, but no gain.
I mean, seq+autoclutch should simulate the use the H-Gate of the car its simulating, right? So it should NOT be faster than real H-Shifter shifting.
For example, RB4+AS2, I'm 1.5 second faster with seq+autoclutch. Yet , witch H-shifter i can't shift faster.
To answer to OP, H&T can make you faster IF you'are already using manual clutch.. if you compare to autoclutch + seq , you will be slower.