Note for British readers (and maybe others?): in the US, "cider" means what we call "apple juice". (In the UK, "cider" means what I think you call "hard cider", an alcoholic drink made by fermenting apples.)

(Actually, I think it's a bit more complicated: in some parts of the US, "cider" means what we call apple juice and "hard cider" means the alcoholic stuff, but in other parts "apple cider" (which is what Jeff wrote here) means what we call "apple juice" and only without the qualifier does "cider" denote the alcoholic drink. But here in the UK, "apple cider" definitely means something alcoholic, even with the qualifier.)

I would assume that applying this procedure to what-we-call-cider would get rid of all the alcohol, since it gets rid of most of the water and alcohol is more volatile, but it is less sweet because some of that alcohol "used to be sugar" and probably there are other flavour differences.

It's also available commercially, e.g., from King Arthur Baking. It's usually called something like "New England Boiled Cider". It has a long and interesting history linked with the anti-slavery movement, since it was an alternative to molasses which was produced on sugar plantations in the South with slave labor. It fell out of frequent use sometime during WWII, I dont' know why.

I use it a lot in apple pies, as a way to amp up the apple flavor without too much additional sweetness.

There also used to be a popular thing called "Boiled Cider Pie", whose filling was a custard made from this. James Beard has an intriguing variation involving grated apples that's in my kitchen queue.

Your 8:1 reduction is more extreme than I've seen before; usually recipes go for 5x or 6x reduction.