I am so grateful for Christan's help over the years. We talk often of my first visits to Edwards when I was at IU and Northwestern in the late 90's. My M.O. hasn't changed much, I have a clear idea in my head for what I want to sound like and I have a recording device with me (Zoom Q8 in this case) to verify how close I'm getting as I try various tweaks like different bells, slides, lead pipes and now mouthpieces.
Two things most students don't do is use their own ears both in research and when choosing equipment. How much are you listening each day to great recordings of what you want to emulate? Is it only trombone? When choosing equipment do you listen more to the expertise of people helping you choose a setup or is it yourself? Although Christan is a total rockstar for ears and expertise, any person in his position won't be there when you perform or practice so it is extremely important that you can hear what you're looking for.
Most importantly, the upgrade you're looking for must be a sound product available on your worst day. Too often people choose equipment that is much to large that only sounds good on their best day. This is a lot like shoe shopping with my dad when I was 8 years old and we'd buy shoes sized 1 and 1/2 size too large so I'd have room to grow into them. I was eight and the most I was doing was chasing girls or running from bullies on the play ground, so it was cool if my shoes had room to grow. You're buying a trombone to do very specific things under tremendous professional pressure even as a student, so a perfect fit is imperative. Christan had a great analogy: Don't make the mistake of buying Nike Air Jordan's the exact size of Michael Jordan's foot and expect to move around the court or even shoot like him.
Trombone players get pressure from other trombone players to play loud as if that is the peak of artistic greatness and this drives them to play enormous equipment. They don't trust their ears or their body and go too large hoping they'll grow into it. Unfortunately they then struggle to play with clear articulation or in the upper register and sound like moo cows in the back row. I'll admit I've fallen down the big equipment rabbit hole more than once and I always conclude the same thing - I don't want to be Michael Jordan, I want to be Bruce Lee.