I'm never getting a board with Costar stabs [Filco] again. I'm typing this on a Filco Majestouch 2, and the stabs don't play nice with a wide range of aftermarket keycaps. [Whereas Cherry stabs would be less problematic.]
I think the Costar stabs on the Filco were designed basically for thin OEM-profile ABS, and that's it. You can get SP SA R3 on there too.
The stabs are rattly and noisy if anything is even a tiny bit out-of-spec.
Contrast this with the Varmilo VA87M I received. Beautiful, buttery stabs, feel like they've been lubed from the factory. Took aftermarket keycaps without a problem. Quieter, too. Sure, Cherry stabs aren't as teeth-clenched rigid as Cherry, but who wants that?
I own a Majestouch 2, and my next keyboard will be a Leopold FC900R PD.