Just watched an Interesting video by Bryon Fulcher, principal trombonist with Philharmonia Orchestra, where he demonstrates how the orchestra uses the euphonium on occasion. Pretty interesting from a trombonist point of view. Early on in his career he needed to play the 'Bydlo' solo from "Pictures at an Expedition" (Mussorgsky) with one of London's finest orchestras. At the time he didn't own his own euphonium so had to borrow one. Here's a link to how it went. Pretty funny.

https://www.youtube.com/watch?v=l5aomOpZoaU&start=1316