I'm actually curious how many GMK and KKB sets try to run and are cancelled in comparison to one another. These numbers are probably off, but looking at Keycaplendar in the past year (from March 2024 to now) they show 45 GMK sets and 16 KKB sets run. Those aren't all traditional GBs though, and include some where large vendors do a preorder. A handful of the GMK ones are just smaller add-on kits (although I'm not sure how that affects the odds of being canceled, def more niche though), and I dunno how CYL vs MTNU might affect things. This includes some GBs that are still ongoing, but several GMK ones have recently hit MOQ (e.g, Black & Gold, GMK Verdant Retro). Maybe some canceled ones aren't listed on Keycaplendar though, or I might be miscounting of course.
In that time period I only see two canceled GMK sets (Lilies of the Valley and Hippo). There are four canceled KKB sets during that same period (Buff Bride, Verdigris, Yōkai, and Henchmen). It does suggest that GMK sets have a significantly higher chance of succeeding, though I'm sure so much is set dependent. KKB I think makes lower MOQs possible? I'm not a designer so I'm not sure.
Someone like Dvorcol could do a way better analysis though.