One advantage about local LLM: You could serialize the context yourself, without being constrained by APIs. And let's not forget, the Big 2 encrypt their thinking. If you use custom clients, which is a very grey area alreay, being able to produce the context string raw is a big bonus. Takes away a lot of annoying constraints and needless mystique/obfuscation.
But I don't know how usable GLM 5.2 is vs the Big 2.