The vintage Symphonie and Classic are small bore. I've had them and even though they are very well balanced and easy to play I found that they limited my expressionism (ease of more extreme dynamics). I'd definitely pick a LL or Dynamique/Dynamic above them especially if you are going to need the extra oomph in jazz. Mouthpiece-wise. it doesn't take much to get more power from them. For instance if you used a Vandoren M13, a M13Lyre would definitely work much better. But then so would a 5JB jazz (which is much more open). I've found I use different mpcs for different genres. If I was going to play chamber music I'd use a M13 Concert band - M13lyre. then for more omph I have some vintage Woodwind K9 pieces that I use a lot. As for more modern mpcs, it all depends on what you currently like, and what other options are available for the brand/model. But the most important thing is learning how to play that new mpc. If you use the same embouchure/technique with a new mpc you'll end up just sounding the same with other technical issues. I should also mention that I'm not a fan of Long Facing mpcs. I tend to stay in the Medium facing range for mpcs as it allows the reed to give a nice crisp response.