EDIT Just read your question again: If you look at the sample images (link some posts above) you see that the DS lens makes smaller bokeh balls, but with a nicer (= missing) outline. /EDIT
The apodization filter works like an aperture but with a gradient - not a hard transition between 100% transmission and 0% transmission like a standard aperture. Usually bokeh balls are images from the aperture - at f/8 you can see very often the number of blades, wide open you see the aperture defined by the smallest "hole" in the light path. The apotization filter close to the aperture blades makes a soft transition of clear in the center to dark in the outside and the bokeh balls reflect (not optically) the softer transition from the bright center to the dimmed outer regions.
Another argument for "clear in the center" is the fact that stopped down the DS lens works like the non-DS lens. Here you use only the clear part of the "filter" hence there is no difference to other lenses.
If you want to experiment a little bit cut out a star shaped hole with the outer diameter of a bright short tele lens and put it on the lens front. Wide open you will see a star shaped bokeh, stopping down the effect is vanishing because the effective aperture is inside the star shaped hole. And if you do not like to bother with a star shape, use a flat rectangle to make rectangularish bokeh "balls" ...
Here an example (I am trying to avoid some work I do not like to much ...
The pattern to hold in front of a lens (in my case the EF-M 32, f2/100mm would be better, diameter of the hole (external) ca. 20mm)
View attachment 187013
Now @ MFD & f/1.4 - star shaped bokeh "balls" - if I had opened the lens and put the paper in the aperture plane the outer stars wouldn't be so crippled, but I like that lens and disassembling is much easier than assembling
The lowest "star-circle" bokeh structure ist partly limited by the star in front of the lens, partly by the builtin aperture)
View attachment 187014
And last image MFD and f/8 or f/11 (now DOF is so deep that you can see the pattern in front of the lens but the stars have vanished from the LEDs but you can see the 7-blade-heptagon (o.k. if you look with the knowledge that the EF-M has 7 pblades) on some "bokeh balls"
View attachment 187015