Interesting. I wonder at what point a fin slot is preferred over no fin slot for MD?
Based on my experience, 75mm & up, you do NOT want a slot.
Airframe structural integrity more important.
54mm & below [with the exception of extreme motors like the Loki M or 38mm L] not that significant.
I don't want any slots in any size.
I am also guilty of modifying slotted kits to minimum, but either replace fins with carbon plate [same thickness as stock or thicker stock G-10]
More importantly I don't want thin wall tubing in 75mm & larger!
So far smaller rockets have held up with thin wall.
Column bending becomes the airframe issue.
When designing a minimum diameter, usually built around largest motor being flown.
I would suspect those doing this would be knowledgeable enough to know proper parameters.
Issues abound when less experienced jump on the band wagon, and try modifying kits slotted for MM and going Minimum with thin fins, not up to stresses involved.
''Can you say...deconstruct before motor burnout"
Simply replacing fins, with proper fin stock usually alleviates problem or tip-tip to strengthen.
As usual when it comes to Xtreme projects, there is no simple one answer fits all.
Simulations are your best friend! [before building LOL]