I'm all for it.
He has some great weapons to control, and also some pretty good magic animations.
One issue, though: he will not look like he does in Witchaven's games, because the palette isn't the same as Hexen's. As RambOrc said, the work to import the graphics to Hexen isn't that big (better than draw from scratch), but color distortion caused by the palette change will make it look different from the original version. It isn't exactly a Con, but just to let you guys know.
Since I'm holding the games here, it's my duty to make the conversion, so this is on me.