Here is a link to a page about a record which came out a couple of years ago called "The Regent's Buge", featuring various instruments that are no longer in vogue - various keyed and slide trumpets. But evidently not including a slide bugle, or a keyed bugle.
Still it sounds as if it would be an interesting record to hear.
I wonder how it is that some instruments survive and others get forgotten? It doesn't seem to be just a matter of which make the best sounds or are easiest to play well.