Re: Vandoren A55 Blue Jumbo
I do not have a CE Winds tip opening chart, but if it is a 6, it is likely around .076" tip opening. The 5 spot is a jazz mouthpiece, and has a sound similar to the old Meyer alto pieces. As such it has a slightly spread tone and does not project particularly well.
On the other hand, the Jumbo Javas have a much more focused tone, and project very well. The A55 Jumbo Java has a .097" tip opening which is almost like having a 9 or 10 size in other mouthpieces. Given the way the Jumbo Java projects, you might find that the A45 is all you need in a tip (.087").
You asked if anyone had experience with the blue A55 piece. I tried a black A55 JJ a few weeks ago, and found the tone to be a bit darker than the A35 that I actually bought. The A35 easily buried Meyer like pieces when it came to projection.
You should be able to find a shop that carries JJ's, or an online shop that will allow a trial. The best way to find what you need is to try it out.