potassium chloride tastes salty but also has a strong metallic feel, it's what most salt substitutes are made out of

I see Aluminium Chloride salt sachets in fast food outlets from time to time.

The last time I tried it, I detected only bitterness, not saltiness.

I also wonder why potassium chloride is not being promoted heavily, in the face of low recommended intake of sodium, IIRC the recommended potassium intake is much higher than that of sodium.

The reason is that there is a lot of overlap of patients with hypertension and chronic kidney disease. When your kidneys don't filter as well, one of things that your body holds onto is potassium. High potassium levels (among other things) cause cardiac conduction issues and arrhythmias which can be fatal if not intervened on. I. The general population we have to be careful that we don't trade one problem for another.

On the other hand, _low_ potassium can also cause heart problems. You just can't win!

That's true as well, fortunately(?) it's much harder to get to cardiac issues with hypokalemia than hyperkalemia (most commonly I see it in anorexics).

Most causes of low potassium are side effects of medications, or short term losses from diarrhea or vomiting. There are some people with genetic causes of excess urinary potassium losses but it's pretty uncommon.

For cooking I use a mixture of sodium chloride, potassium chloride, magnesium sulphate (50:40:9, the remainder is iodine) tastes just like pure NaCl to me. It's a brand called Seltin here in Norway.