Well here's my take on it... it depends a lot on your limb design. In very high performance designs where you aren't leaving much on the table, the heavier veneers can make acnoticeable difference if you are carefully testing them on a shooting machine. Both Sixby and i havevnoticed as much as 5 FPS difference between Ebony and Myrtle veneers at .020- .025 thickness....
But.....i would have to honestly say ...for the average bow being built today, most archers would never notice a bit of difference. i don't know too many guys that can see 5 fps difference shooting close yardage anyway.....
For the discriminating customers looking for high performance, It all adds up... The veneers, the cores, and the core to glass ratio matching the the draw weight....It all makes a wee bit of difference. 2 fps here. 3 fps there, 5 fps for veneers... Like brutha Steve was saying...next thing you know you can seriously see the difference.....
Kirk