analog newbie question/vinyl weight

I'd say one millimeter is one millimeter on either end, and change in VTA is a change in VTA. For simplicity, if you started parallel to the record surface, I don't see how one millimeter on one end could result in completely different SRA than one millimeter on the other end, except that they would work in opposite directions. But I've been listening till 5 am and doing extensive damage to my Scotch reserves so someone with a clear brain please chime in.

I just checked, and Mikey's math is correct. A 9" arm describes a circle with a circumference of about 1,436 mm. Since there are 360 degrees to a circle, that would mean 1mm translates to about 1/4 of a degree.

As legendary as Mr. Fremer's listening acumen is, however, in this case he doesn't substantiate that the 1/4 degree difference isn't audible. I have a tonearm with very easily adjustable VTA, but it's only a 6mm range. That's only about 1.5 degrees of total range. Why bother if it's inaudible? Yet I often raise or lower by 1 to 1.5 mm to get a little more transient attack (higher at pivot) or more fullness and less stridency (lower at pivot). I also have noticed that my 200g pressings tend to sound a little rolled off and bassy unless I raise the arm about one mm.

Adjusting VTA to get more fullness or upper frequency extension is certainly not a novel idea, and if I had a tonearm that allowed easy adjustment, I'd probably experiment with it. However, most tonearms don't allow hassle-free adjustments; I have to loosen and then tighten 2 tiny screws on my Classic tonearm to change VTA. If I wanted to get VTA "right" for every album I was listening to, I'd be doing more adjusting than actually listening. This plus the fact that you don't know the precise angle of the cutter head for every single album make VTA adjustments seem rather impractical to me.

On my tonearm, one revolution of the VTA knob is 1/2mm, assuming I am moving between LPs of similar thickness (weight). IME with this arm, adjustments of less than one turn often result in better timbres and tone. No doubt, the arm has to be capable of making incremental VTA changes easily (on-the-fly VTA/SRA is most desirable) and also capable of allowing the cartridge to present the results.