So I took a look and here’s what I saw comparing a phase version of the CF N 10/0.30 Nikon with a brightfield version. The brightfield Nikon CF N 10/0.30 Plan Achromat produced a slightly better stack. Not by a huge amount, but it was noticeable, especially toward the edges. I’m always leery to judge by the stacked images so I compared similar individual frames and the conclusion was the same. I can’t say if this is simply a lens “sample” variation or whether it is due to the presence of the phase ring.
One thing I did notice, that was obviously due to the phase ring, was the appearance of out-of-focus areas. Now I realize that “bokeh” is not a concept used too often by us stackers

If I already owned only the phase I would certainly use it. Both are capable of producing great looking images. But if I were looking for an objective with the primary purpose of putting it on a camera bellows I would probably skip the phase version and keep looking until I found the brightfield.
This subject was chosen only as a “test” (not intended to be a pretty picture!). Both images treated exactly the same. Slight sharpening after resizing, and that’s all.
brightfield objective

phase objective

part of single image from stack. Phase (top), brightfield (bottom)
