Personally I’m glad that these epiphones are coming out. This way I can try out the body shape and make sure it’s not too bulky before ordering a build from decibel sound implements.
Jazz bars should just sound like jazz bass pickups but in a soapbar housing. Big singles are in the jazz family but they’re bigger. I think you’ll like jazz bars more.
I think it depends on what IR’s you’re using how much difference you might hear. You’re not just hearing the speaker, you’re hearing the cabinet the speaker it’s in, the microphone(s) used to record it and then outboard gear.