Many years ago I was looking at a Morse 1 Dixon QC holder and wondering why did they bother making it. Then I thought what if I mounted a DTI in it, best mod I ever made.
I cannot for the life of me see why any sane person would mount a DTI vertically

, when , if mounted horizontally, you can use the cross slide for coarse adjustment.
Once you get a bit of experience you can centre quicker than using a collet, well you can if you had to change the collet, that is.
Ned