Thanks again,
Dumb question, but what's the purpose of removable cores anyway?
I have read a few folks comment that they have broken off the stems on presta valves. Some apparently do it somewhat regularly. Without a removable stem the tube is shot after the stem breaks off and the valve core falls inside the tube. Also the valves do rarely go bad and being able to replace them avoids changing the tube. I have done that, but only very rarely.
I figure the main advantages are adding sealant and being able to more easily seat a tubless tire with fast burst of air, but those certainly weren't the originar reasons.