Oh about your mouthpiece the berg larsen rubbers generally arent very widley used for classical. It could be that you have a big facing or more importantly a baffle built into the mouthpiece. Do you know the facing/table numbers written on it? This might help you figure out if its a mouthpiece problem or a personal problem.

The "1" means that your Berg is on the brighter side as far as the baffle is concerned. They're not obnoxiously bright, but I can see why it might be a bit much for a concert setting. Really, the bari sax should blend with the low brass - fairly mellow unless fff, know what I mean? If you really like metal, the Otto Link Super Tone Edge pieces are mellow-ish and could be used classically, but still may be edgier than your director desires. For classical, I find the S80's and Larry Teal "LT's" a good piece. There's no baffle, and the chambers are fairly open. The LT is round-chambered and, to me, blows a bit more freely than the S80 square-chambered pieces. I'll warn, though, that C* is a VERY closed tip opening (same for LT), so as a jazz player, you'll absolutely hate the C*/LT facing. Though the tone is appropriate, it will feel like there's a towel stuffed in the end of your horn when it comes to volume and expressiveness. I recommend for bari probably an "E" facing if you're used to more open mouthpieces. My last bit of advice is to give yourself time when switching to a classical mpc. You may not like anything you try, but it may be the right sound your director is looking for. Be patient. Good Luck.

Actually, the old ebolin Brilharts aren't a half bad legit piece for bari. Especially when combined with the Alexander Classique reeds.

A good classical mouthpiece would definitely help. I have a Selmer C* myself, and it is quite decent (although, I imagine there's betterconsidering that's the only classical piece I've ever tried). But a lot can be done to your embouchure to warm up your tone. Try using more mouthpiece (moving your top teeth further down the mouthpiece). Also, (this helped me a bunch) think of your embouchure as rounder and breath from your stomach, rather than using more of a tight, airflow from your neck strictly.