point source v. BL
If by "point source light" you mean NuArc, FWIW I mention that for several years I used both NuArc & fluorescent bulbs, & from time to time just for helluvit ran comparison 21-steps.... never saw consistent difference of any kind in VDB, Cyano or gum.
The BLB bulbs (which my neighbor had) were much slower, tho I never used them enough to note other differences.
I add however that once in a burst of purity I replaced broken vacuum frame glass on Nuarc with I think it was "Starfire" -- purest glass known to humankind? Horrible for gum... I had to re-replace it, tho I think it's still in my cellar somewhere. (Ordinary plate for replacement was fine.)