I currently play an Edwards Alessi Model, T396-A, with a Griego 55 mouthpiece. I play this equipment because it helps me sound the way I want to sound in the various settings I find myself playing most often, namely solo recitals, brass quintet, and occasional large ensemble playing. I don't make a dime as an Edwards artist, and I don't make a dime off of any Edwards, Getzen, or Griego product purchased by my students. It is a relationship built on trust in great products and those who make those products.
My students play all kinds of trombones! If you attend a trombone studio recital or trombone choir concert, you'll see Conn, Bach, Getzen, and Yamaha trombones, and even more variety of mouthpiece brands. Most often, I suggest a 5G sized mouthpiece if you play tenor, and something near a 1 1/2 G for bass trombone. Over time, we work together to tailor equipment to what best suits the student, but these are solid starting points. My bass trombonists really enjoy the sound and comfort of the Griego GP mouthpiece, but both of these students found this mouthpiece on their own.
Bottom line? I've been primarily a Bach and Edwards player over the past 20 years, and the majority of that time has been with Edwards Trombones. If I saved the money I spent on various models and variations on models though the years and spent it on lessons with master players and teachers, I'd be further ahead in my playing than any new trombone could possibly help me achieve.
When you've practiced your way into better playing, you'll have better insight into when it's time to make an instrument change. Then make the trip to Elkhorn, Wisconsin and have Christan and his crew help fit you to a great instrument. :)