Has anyone ever tried running a smaller or larger ball bearing so that it runs in an area other than the normal wear groove when that grove on the cones usually gets pitted? Wondering if a size down or up would accomplish as the cones seem to have a lot of radius to work with and perhaps the cups not so much.

It has been mentioned elsewhere as a possible solution. I'm not sure if there were or are any suggestions as to why not so... why not. I would expect that it is the cones that are more likely to wear or become pitted than the cups because they are more heavily loaded. Cones are more easily replaced assuming you can source something suitable so, if it is the cones that are the problem, I would be inclined to replace them.

The cone does not "usually" get pitted if properly maintained. I have had hub and other bearings in the past last for many years and thousands of miles without pitting. In fact, I highly value a hub that has some wear, as the cones and cup wear surfaces are much smoother than when new. As noted, if only the cone is pitted it's better to replace it than to try such a hack, as the bearing will not operate as well and could be difficult to adjust.

Everything on a bicycle works together. You can almost never change just one thing without the change affecting something else. In this case, using larger or smaller bearings will affect your hub's over locknut dimension. I wouldn't bet on that not causing a new problem of some kind.

Aaron Goss, (Aarons bike repair, Seattle) showed how he re ground cones with 2 drill motors..
1 spins the cone ,1 turns the die grinder stone bit.

+1. It can be done, but you will need to be handy with cones and spacers to get the OLD correct again in the end.

The front wheel on my 1988 Diamondback came to me with 1/4" bearing balls, which seemed weird, but the OLD was right. When I replaced the long-abused cones, I didn't have many choices for the 8mm axle, and the new ones were longer, so I needed to use 3/16" bearings to make everything work out. I have no idea if I'm closer now to how the wheel came originally or not.

which will remove the CASE HARDENED SURFACE of the cones.... sure feel smoother for a few miles though!

+1. I know some people regrind cones, but the original hardened layer is very thin and the "soft" cones won't last as much (a lot less in fact) as new ones.

He, as i gather, does the work for un replaceable parts from very old bikes

may be able to through harden them easier than case harden them when done.

"through hardening" or Flame Hardening, requires a different grade of steel, and a couple more steps to complete.... Case hardening is cheaper and quicker in large lots.... plus, case hardening only hardens the surface about 2-3 thousandths deep(at the most!)... this leaves the inner material of the part more ductile, which reduces fracturing.

there are other hardening techniques available.... look it up... ;-) and i'd bet the cheapo cones are not hardened one bit, other than a black oxide coating.

as to the original post... i've run into many hubs through the years that had larger balls in them... bad move! in all but a couple cases, the cones had been totally ruined as the balls contacted the cone at THE VERY SMALLEST EDGE of the cone... remember that fracturing i mentioned above? yep... the lip shattered, filling the grease with bits of really hard metal... the entire hub and axle set will be ruined if used for very long... BMX riders do this most often... along with not putting ANY GREASE in their bearings at times... seriously... NO GREASE!!!???!!! some stupid rumors run amok..... sigh... i hate lacing 48 spoke BMX wheels...

My commuter sees 6000+ miles/year.
The current rear wheel has reground cones. As of 15 000 miles or thereabouts there are no undue signs of wear compared to unground cones.
So I don’t know. The argument about case hardening makes sense. But it is not supported by my experience.
I had a go at case hardening reground cones before use. Quite tedious.
But friends in the automotive business laughed at me. ”things that small gets hardened through and through” they said.
So I tried installing some fresh off the grinder, and it seems to work just fine.