Better to have it and not need it, than to need it and not have it, right?

I have no intention of using it solely, though it is a soap I regularly use at least 3 times a week.

I've gone through at least two pucks of MWF, using them exclusively. I think I've done the same with a B&M puck and one SV puck. I tend to stick with something for a while before I change it up. In total, I think I've used about five pucks of MWF before this reformulation, and I'm a firm believer that MWF performs best when used regularly, so once a puck is going it gets used frequently.

Kent is now out of tallow pucks, so the cheap and easy source of MWF has now dried up.

The last couple hundred were from batch 2375, which must be 25 years old at this point. They must have been very well packed and stored, before being forgotten somewhere in Kent's storeroom(s). My brother-in-law says they smell just as strong as his other Kent pucks.

...and Kent added more pucks. I don't know where they keep finding them.

I've been doing quite a bit of research into this, and I'm curious as to why you think so? It's said to be a low risk/low harm ingredient.

Let's get the nasty stuff out of the way first.
It's made by combining formaldehyde and sodium cyanide. Which are both carcinogens, but the final product is not a carcinogen, and never breaks down into one. Some animal studies have found Tetrasodium EDTA have reproductive effects, however, only at very high doses--because it's able to bind with metals, high doses are thought to pull zinc out of the body, causing deficiency and thus illness. This is not a risk when used in cosmetic items and only shows fetal reproductive effects at levels that are outwardly toxic to the mother.

Now the better stuff.

It helps to prevent the formation of mold, yeast, or bacteria in the soap. This acts as a preservative both in dry storage and while the soap is being used.

It binds to hard water ions, such as magnesium, iron, and calcium, softening the water used to make lather, this increases and improves the lather, and also prevents the formation of soap scum.

It acts as a skin penetrant, helping other products in the soap penetrate the skin, like lanolin. It is important to note that while it assists other elements of the soap to penetrate deeply into the skin, it doesn't do so itself.

As long as you aren't eating the stuff, it doesn't seem to be so bad, and for the things it does, it doesn't seem to be an easily replaceable all-in-one ingredient, without negatively affecting the soap in some way.

Mitchell's has always had their shaving soap made by an outside manufacturer. It's possible the manufacturer also makes T&H's soaps. The formula is also similar to Claus Porto's Musgo Real too, but I think we can safely say that particular soap is made in Portugal.

The new formula isn't bad, and it's still a decent soap. Cartridge and DE users will hardly notice any difference. Straight razor users won't be happy with the reduced slickness of the new formula, but most people will likely accept the trade off, given the new formula lathers easier.

It will be interesting to see what happens, not only with MWF, but Trufitt and Hill, and Musgo Real, in six years when the draconian E.U. and U.K. restrictions on palm oil use kick in. Will it cause a return to tallow? No one knows.

That sucks. Pretty much all of the original scuttle makers have ceased operations. There's a few new ones on the market, but the old ones from the glory days of the wet shaving forums (10+ years ago) have been gone for years.

Edit: I take it back. Georgetown Pottery still makes scuttles.