This whole business about what horns are "professional" is a digression.
Over my entire career as a performer, I have made 85% of my euph-playing
income playing a Yamaha 321. (Avatar pic was taken at an outdoor quintet gig. I play the horn parts and do most of the arrangements)
Nobody outside the "euphonium bubble" or "academic bubble" knows or cares what horn someone plays.
They just want to hear the tune.
I've been playing for pay for almost 40 years. NOT ONE person in a regular audience
(outside the "euphonium bubble" or "academic bubble") has asked me what type of horn I played.
Most people had no idea what a euphonium is, let alone cared that I wasn't playing a Willson.

Having said that, I never once even contemplated leaving my very nice day job! ;-) ;-)