I recall hearing in one of Steven Mead's pandemic videos answering a question from a reviewer about this topic. Steve said he could do it, but didn't advise it for most players and he seemed to imply that there was a tonal penalty for using this as well - he seemed to say he didn't think the time to invest to acquire the skill was worth it and he also said he almost never uses it himself - and if a player at his level almost never uses it, that speaks volumes to me.
- Scott
Euphoniums: Dillon 967, Monzani MZEP-1150S, Dillon 1067 (kid’s horn)
Bass Trombones: Greenhoe GB5-3G, Getzen 1052FDR, JP232
King Jiggs P-bone