[Barotti]

Pen works really fine on SP3 with Windows 10 and DuOS.

And it works not only as a pointing device but as a pen for writing annotations in MSPro?

I think there shouldn't be any differences between SP3's pen and SP4's.

Barotti, how did you do that?
Any special driver installations?

Sorry, nothing special done. Pen works fine for annotations, just like your finger does, but more precicely.