Here's a few thoughts....

There's no way to know if any of these colors are "good" choices because you don't mention any details about your decor. Flooring, furniture, art work, and a dozen other elements go into selecting a paint color.

Adding 25 to 50 percent more formula to classic gray will not make the color dark enough value to have an LRV of around 50. And that is a fools errand anyway. You are better off selecting a paint color which is in the value range you want.

When I am selecting a color to coordinate with a gray in an adjacent space, I do not select another gray. Possibly, I will pick a near-gray which has an undertone unique to the other room. The point is, there are other neutrals you can select from which will be more dynamic, create clearly distinct spaces, yet still be harmious.

Consider hiring a local professional, one who is an expert with color.

That is a good point. I didn't mention décor details, because the house will be sold this year, and I am trying to go for a neutral look that would appeal to many buyers. Of course I want to like it too, while still living here. I love gray, which happens to be a popular choice, so I am happy playing with shades of gray. But I would welcome any suggestions for other colors that harmonize with gray on adjacent walls. Here are some pieces of furniture that I have:

Dining room table - Flatiron from RH (still looking for chairs, I want mismatched chairs to go with it, some weathered wood, some painted):

Breakfast nook: white pedestal table

Chairs are like these, but bluish/green - no longer sold at PB, so can't find photo:

Red cabinet in living room:

Family room:

Finish on the console is espresso elm:

RH English roll arm sofa, color is charcoal:

Sold the old coffee table, haven't chosen a new one yet. There is also white built-in shelving in the family room, and a red-white-gray brick fireplace, similar this one:

The floors are your standard 90s yellow finish oak, I plan to refinish them to weathered oak or a driftwood-like finish (so that all orange/yellow is gone). Carpet is this (color is "Platinum Mist" - gray):

I hope this helps. Thank you again for your time and advice.

You have nice, masculine and neutral color furniture. Since these items are mainly charcoal, espresso, and weathered wood tones, I would suggest some "slate" grays. Look for undertones of blue-grays and green grays and use each in the adjacent space.

From your first post regarding BM London Fog, you mentioned it may have too much contrast with classic gray. And it probably would. The good thing is this demonstrates you are thinking about contrast and trying to strike the right balance. This will be key- varied undertones alone is not enough to differentiate spaces, you also need contrast in value.

As an example, look at these four colors which all are harmonious neutrals but have distinct undertones and different values (essentially LRV): SW 7644 Gateway gray, SW 7657 Tinsmith, SW, 7641 Collonade Gray, and SW 7653 Silverpointe.