Mouthpiece tip charts are just a close idea of what they should be. I have had original Bergs and Links that aren't that close in tip size to what these charts say they should be...but they were original. Along the same lines...mouthpiece value charts are just an approximation too.
Theo's mouthpiece value chart in MANY ways, is WAY off in value. A lot of guys look at his chart as THE reference, and now many pieces have double or tripled in perceived value, and others are way lower in value on his chart than they actually go for in todays market. Mouthpiece tip opening charts are closer to reality...but not always accurate either.
Guardala would make custom pieces for guys all the time and put whatever tips the buyer requested on those pieces. I have had MB's that measure .107-.122 and were all original. Dave told me that guys would want the pieces but would want them a little bigger or smaller than how he made them, and he would customize them for the buyer.
"I want a Brecker, but I want the tip around .120, "cause I like to play a 9 tip." Stuff like this happened all the time Dave told me. So now many of his pieces are floating around that came right from Dave's shop originally with different tips than whats published on these tip opening charts. Also, a lot of pieces he'd bring around to various shows, were quite different from the ones you read about. ALOT of prototypes of his are floating around, that were original from Dave. I think Theo and others have done a good job overall, but there are variables and market swings that make a lot of whats written, something to take with a grain of salt.
I've been asked many times to put out charts on mouthpiece comparisons, and values...but its a double edged sword, and it would do more harm than good, in my opinion. What I hear as to the difference in two pieces...you may not hear at all, and not agree with my findings.
One time Bergonzi came over my house looking for mouthpieces, and he heard me on a piece that I thought would be perfect for him, and he said it sounded too bright for his taste. I washed out the piece, he tried it...and loved it! It sounded Way darker for him than it did for me. Thus, describing comparisons between pieces is too subjective to be accurate.
Mouthpiece values fluctuate so much too. I have seen original Slant 8 tenors go for $750-$1550, depending on how the market is at a certain time. I have also had original Link Slant 6's that can measure .088-.096 opposed to the .090 they are said to have had if they were original.
Just a few thoughts from a guy that has seen ALOT of mouthpieces.