I have not written you for a long time .... I had a big breakthrough finally connecting my lower register to my upper one. The mpc change helped a lot, giving my lips the needed space to MOVE! Now lip slurs on 3 octaves are just a fun game for me! My embouchure is more flexible than ever and shows a real continuity. There again, my mpc allows my lip to move freely and get the most efficient shape to hit the highest pitches. It's weird, but holy potato it works! I still have to refine my endurance... but with BE I know it's just possible... patience will be the secret for that one!
I can make my low register rattle like on a bass trombone (you should see the looks on my directors face when I do it), and when I slur up to a full high C, other horn players look puzzled (how come a guy who's been on the horn for only four years can do this...) even professional players. I discovered that very few can play on more than three and a half octave with a full sound! But the real thing is now I can take time to practice other stuff than BE (scales, lip trill, and repertoire)