Shutter speed when recording with DSLR
On DSLRs, a fast shutter can actually be better.  DSLRs scan the image to sample rather than capturing the whole frame at once.  This is why you get a distortion when you do a rapid pan.  A faster shutter will result in stopping motion more clearly (less motion blur), which can seem a little harsher than the softness of film, but a sharper image may be preferable.  That said, a good ND shouldn't have a significant impact on image quality.

So, my final advice is, if you want crisp frames with little motion blur, use high shutter speed, if you need smooth motion for things moving around a static scene, a high quality ND is probably better.  If you simply have a fairly static shot, then shutter is probably the way to go again.