Will Shimano adapters fit with other brand disc calipers? It seems as though they will, but I would like to just double check before spending $300.
Yes they should fit, just make sure you're using the exact same size rotor as the adapter is made for. e.g., don't use 185mm rotors with a 180mm adapter. or 200mm rotors with 203mm adapter.
Keww... For sure, 203mm adapters with 203mm rotors.