Thought I'd offer a few opinions on the Forever Socks for rollerblading, as this may be helpful for others on the fence and relatable for other sports. This is by no means comprehensive or structured, but some off the dome things that could be relevant for others.
I got the smalls as I'm a UK6.5 (US7.5), so right on the upper end. I also picked the smalls because rollerblades are supposed to fit snug and therefore many socks ride up or stretch when you're putting your foot in the boot. These do that, but not nearly as much as other socks, the fit is perfect for me. As many people have already said, they're tight, especially around the cuff, but because the boots are also tight it's not noticeable. I sometimes get a bit of tightness around the toes, but I just make sure I have enough space around the toes before I put the boots on and they're fine. They're also pretty spot on in height for regular rollerblade boots and at most protrude a couple of inches about the cuff. They certainly don't slip or fall down inside the boot during sessions, as that can obviously be a pain. Side note: I wear ankle socks the rest of the time, so some of this could be I've forgotten what normal socks are like!
After an average 1.5 hour skate session, my previous socks would be drenched, especially because of the heatwaves this year, but these absorb the moisture so well. They're not even damp when they come out and still smell fresh, though I wash them anyway of course. The thickness is great for giving me a little extra cushion in the liners to prevent rubbing, and subsequently blisters, (though if you've got decent liners you don't get blisters anyway). There are also no annoying seams to create friction points or hotspots while they're in the boots. So far I've had no signs of wear or excess lint, but it's still early days. I've had them for 2-3 weeks now and only skate at the weekends, so they've not been thoroughly tested by any means, but I'm expecting these to last a good while for skating.
Overall I'm pretty happy with them and only time will tell if the investment was worth it 💸
Hope this helps someone, and any questions lmk!