@ZipLine-- I actually think that you're in the right mindset when it comes to buying a new mouthpiece. It's great that you're getting recommendations and actually trying different mouthpieces before buying them. That is definitely the way to find the right one for you.
My advice is to not get too stuck on a brand or number. The comfort of the mouthpiece and the quality of sound is more important. Don't rush yourself. Go back to the shop to try the same mouthpiece three times if you have to. If you find one that feels very comfortable and gives you good sound, go for it.
Since you're an intermediate, make sure that the mouthpiece is not too narrow or wide. You still need more practice and control over your technique before switching to a narrow one.