Okay I just tryed with the H one and it didn't change anything at all
so 2 posibilities
1: You have THE pen that dosn't have the issue (unlikely)
2: by using an hard tip you draw differently wich make the taper effect less visible for you (not my case)
and scince my sp4 pen have the taper effect on the sp4 and not on the sp3 it proves that it is either a software problem either an hardware one but of the surface pro 4 and not the pen
the pen have no problem by itself
(btw surface pro 3's pen have the taper issue on surface pro 4 too)
so as I said we have 2 option
1: it is a software problem of the surface pro 4 and the fix would be to update the drivers
2: it is an hardware problem of the surface pro 4 (not the pen) and we couldn't fix anything unless microsft include some kind of pressure stabilisation to it's drivers
option 2 would explain why we still don't have a fix but I doubt
it must be a software issue
so it's a shame that after nearly 4 month microsft still didn't fix the problem knowing that the sp4 is a 1000 to 2.5k dollar computer wich is made by one of the bigest company in the world it's even a shame that we have those kind of issues
so microsoft you have great devlopers so just moove your ****