I have shot both LD and Regular shafts. I came back to the game of pool after a 20+ yr absence. Since coming back to the game 3 yrs ago, I did the switch to an LD shaft. I didn't do it for deflection per say; I did it b/c LD's are thinner diameter, and more rigid. (supposedly). I had to forget adjusting on long runs for deflection with the LD's. That has made life a lot easier.
I have tried many LD shafts, and reconciled on these two,(mind you this is just my opinion). OB (OB2), & Predator (Z2)
I also have an "aged" shaft from a cue-maker with a conical taper.
I like to shoot them "long & thin" so to un-scientifically test these shafts,I shot several hundred "long & thin" shots long table (8ft).
Here is what I found:
Standard non LD shaft -- 1 1/2 to 2 " deflection
Conical "aged" shaft -- 3/4 to 1 1/4 " deflection
OB-2 (laminated) -- 3/4 to 1 " deflection
Z-2 -- almost 0 to 1/2" deflection
I did have a cuemaker turn the Z-2 to a superpro taper, not so sure that would make much of a difference.
I shoot them all (depending on the game), but in rotation games I have a preference for the Z-2.
Both my shafts are 13 mm. My standard shafts are all under 13 mm. I've never taken measurements nor do I care to. My experience is with simply how they play.