Is it worth the effort to sort cases by head stamp when reloading 9mm luger at low to mid range powder charges?

Nope

Effort not worth it for me also.

Unless loading for self defense I never sort pistol casings.

I keep my pistol cases sorted by brand/headstamp. Can't see how cases of different length (headspace in SA or crimp in wheelgun) and internal capacity (pressure/velocity) would do any good in terms of accuracy.

Just buy large lots of once fired brass of a single headstamp.
You will have more uniform brass and you do not have to sort them.

Definitely NO; they are all the same to me. In auto pistols, it don't make any difference.

Makes no difference. Some years ago the bullseye guys did some tests with new brass versus mixed range pickups. Accuracy was nearly the same.

I sort all my brass; load and shoot it in lots. Don't care if it matters or not.

Yes, I know guys who like to do that just because it makes them feel better and they would rather spend time playing with their brass than shooting. It is all good fun, even if of no practical benefit. That is part of the sport.

Negative.

Yup; all Winchester 9mm brass gets tossed into the recycle bin. Years ago the American Rifleman published an article regarding reloading the 9mm Luger cartridge. Bullet set back was severe in W-W cases; so much so a cannelure was needed on the case at the base of the bullet. Mirrors my experience hence no more W-W 9mm brass for me.