I & many others have been on this ‘journey’, although I had no problem using the original Dixon manufactured tool post in industry for many years the far eastern clones on offer today are not made to the same high standard & this can cause operational problems.
For that reason I recently sold my collection of little used Dixon type QCTP & holders & changed over to the Arc Euro trade wedge style lathe tool holding system.
As it uses a different type of clamping system any minor size differences from holder to holder do not affect the clamping strength.
Obviously others will have different stories to tell.
Tony