Just bought the new one last week. So far, very good, though I miss the clip. Can't do a side by side comparison because I lost the old one. Subjectively, I think it's a better pen (except for missing clip). Seems a but lighter in weight. Do not notice any difference in the magnet. No issues with skipping (which did happen with the old pen).
Well I got my own answer. I tried the new pen on my surface. Works and felt the same as original. It felt more like a mechanical pencil so felt "thin" but maybe it's me. I forgot to test corner accuracy. AND tilt still not supported on the SP4.
Sorry, didn't see your post till just now. I don't know. I think since it's hardware in the top, you wouldn't just be able to switch that and still get the new functions. I no longer have the pen. The people at the MS store thought all I needed to do was just update my firmware, which, of course wasn't the case.