The instrument choices today make this question more complex. Some of this post applies to tuba and other instruments, but I will specifically address euphonium. Until the late 1970's, there was a pretty wide line between pro euphoniums (i.e. Besson and Boosey & Hawkes) and everything else. That line was largely drawn by the compensating system, but also included the larger bore of the British instruments. Today we have large-bore, compensating euphoniums that cost less than some student-level ...