I have also seen the same thing on IMS baskets, but not VST so far. I'd say you are right to be bothered since it should have at least a small effect on performance.

Out of interest, are IMS and VST the only two choices when it comes to 'premium' baskets? Are there any other players? I'm currently IMS across the board, and the quality issue is quite surprising.

https://www.espressoparts.com/products/ ... HgQAvD_BwE

Espresso parts HQ14 is pretty good. This is a higher quality version of the traditional double basket, rather than a faster flow basket requiring a finer grind like the VST. There's room to overdose up to about 18g.