About 30 years ago I was playing trumpet in a community concert band, we had an excess of trumpets and no horns.
The MD asked me to look at a couple of secondhand horns in a music shop, not that I knew anything about horns, one was a beaten up Amarti, the other a French Selmer in excellent condition and reasonably priced,
I n a moment of insanity I bought the Selmer, then found a teacher for lessons, I played that horn in the concert band for 15 years until I moved away.
1990 I was invited by a friend to join a community symphony orchestra where the horn section was a Eb tenor horn and an Alto Sax playing transposed parts, at that time I was playing trumpet in an amateur Big Band.
Currently still playing in both groups, Trumpet on thursday nights and Horn on saturday mornings. For a while I found some difficulty with the change of fingering from one to the other, eventually no problem.
Playing 2nd horn a lot of the time I am an octave lower than the 1st, she marks my part where she wants me to go up to give her a rest and she is half my age.
Regards, Stuart