Esterbrook MV Nib Adapter
I got the MV adapter along with a Cobalt Estie recently, and have finally had some time to actually use it with one of my old Esterbrook nibs, a 9028. In brief, it works fine. Fit and finish matches the pen overall, and it feels good in my hand.
The converter looks a bit different to the one shown above, having a transparent knob, rather than the black one show. Function is OK, but it could be improved by including an agitator bead, as the ink doesn't wet the plastic, and can bead up away from the feed, needing a tap or slight shake to get the ink back to work.
I'm going to try a drop of PhotoFlo in one of my expendable inks, to see if it will make a difference. Switching to a different converter would be another option, except that it doesn't seem to fit standard international converters.