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Andrew,
I was playing a Schilke 18 and a Bach 10 1/2C for lead/piccolo before I switched to Monette. I was very happy with the mouthpieces. I had a couple of friends with Monette trumpets that I played, and fell in love with the sound, intonation and overall playability. My Bach was due for its 3rd overhaul and I decided to save the money and take the plunge and ordered the trumpet of my dreams. Monette sent some sample mouthpieces in advance and I never looked back. If I ever had a question, I just sent it to Monette and got (and still get) top quality advice.
What changed? Tone color (more brilliant), resonance (thicker sound), intonation, endurance. Switching from the "standard" Monette to the Prana was the same change again with gains in all of those categories. The Prana does demand a very "relaxed" approach to playing. You do not pick it up and immediately become 500% better.
Read the Monette FAQs on body use and mouthpiece acclimatisation you will get an idea what you need. They have very good information even if you are using other equipment!
The road to better playing has more to do with expanding your knowledge base and less to do with one specific brand. Dave Monette and his crew just relieve me of having to know everything before making a choice! They have never been wrong in my case!