Since there's no "Useless Information" forum, I'll post this here.

About 21 months ago I purchased 3 Synesso 14g ridgeless baskets.
Used one and kept two unused for reference.

Using precision gauge pins on a random sample of 20 holes :

New :
All go 0.014, Some 0.015

Used [ about 2100 shots, 525 washings, 85 chemical cleanings ] :
All go 0.016, Some 0.018

The missus can always pick the used basket by looking through the baskets at a white sheet of paper.

In an uncontrolled test wherein I randomly grab a new Synesso, a new LM, or the used Synesso, I can detect no difference by taste or performance.

Baskets do wear out but I have never worn one out. That would take a heck of a lot of shots. I know some cafés replace them every so often because the holes were larger, as you observed.

cafeIKE wrote:In an uncontrolled test wherein I randomly grab a new Synesso, a new LM, or the used Synesso, I can detect no difference by taste or performance.

Presumably flow restriction is provided by the puck, not the holes in the basket (or you'd have a pressurized crema-enhancing device). As long as the holes are small enough to retain coffee grinds in the basket, it shouldn't really matter.