NovelKeys x Kailh Speed Heavy Switches

I actually haven't ever used any standard browns (Cherry, Gateron, or otherwise) if you can believe it, but to me they definitely feel slightly more tactile than the Gateron Silent Browns I have, though not as quiet obviously.

I believe you're talking about plate mounting vs PCB mounting. Sounds like you have a set of PCB mount switches, these are plate mount switches (https://support.wasdkeyboards.com/hc/en-us/articles/115009270628-Plate-Mounted-vs-PCB-Mounted-Switches). If the Ergodox requires switches of the PCB mounting variety, then these will not work. It isn't specific to swappable switch keyboards though, I don't think, I'm pretty sure it's just the mounting type.

I notice these don't have the plastic stabilization stems like I see on my other cherry mx compatible switches. I still have an ergodox infinity keyboard to put together, could I use these switches on a keyboard that requires soldering? Or are these just meant for the swappable switch keyboards?