2002ss335 is correct.
ARM MOUNTING DISTANCE
Arm mounting distance per se has little sonic effect. It's true every arm is designed for some specific mounting distance, but that distance was chosen for one reason only - to ennable a particular cartridge alignment geometry (Baerwald, Stevenson, Rega, single point, etc.) If a cartridge can be aligned using the intended geometry then the arm mounting distance is close enough. Moving the arm a mm or two will have little practical effect. You'll have to move the cartridge in the opposite direction to compensate and you'll be right back where you started.
Interestingly, if you're using (or wish to use) a non-specified alignment geometry you can choose a non-specified arm mounting distance. I have intentionally mounted tonearms at non-specified dimensions in order to use a better alignment geometry than the one intended by the arm manufacturer. Superior alignment geometry matters much more than tonearm mounting distance.
INNER GROOVE DISTORTION
IGD is not caused by incorrect VTF, VTA or antiskating. Those mis-adjustments sound quite different.
While incorrect cartridge zenith alignment or an inferior geometry do contribute to IGD, in my experience it is mostly caused by inadequate cartridges. I have cartridges that produce audible IGD on any arm no matter how they're aligned. I have other cartridges which do not produce much audible IGD at all, even when misaligned.
Stylus profile seems to be the biggest factor. The finer the stylus contact surfaces, the less IGD. Spherical and elliptical styli are the worst. Line contact styli are better. Micro-ridge styli are better still. It is difficult to set a micro-ridge stylus up badly enough to produce audible IGD.
An inadequate phono stage can also substantially worsen the effects of IGD. This is a less explored area, but it's easily heard and demonstrated if you have multiple phono stages to perform comparisons.
