I ski/race tele which comes with leashes and have been skiing with kevlar motorcyle long underwear on the bottoms. I started when I noticed a few things:
1. I have carbon splinters in my calf from wiping out with powder skis. Don't remember the event but it made me realize there is a sharp edge in that neighborhood as well.
2. My knee pads were actually cut by an edge, if it hadn't been for the hard plastic I think a tendon could have been cut. It also sliced cleanly through the nylon strap. Not the crash that delivered the carbon splinter.
3. I don't recall the skis releasing for either event, tele bindings don't generally release in standard crashes, if they release it means they are broken. But the free heel means that the ski can get in weird places, e.g. you can face plant on your skis and not have them release. Lots of tele skiers wear knee pads to protect against banging the knee hard on the top sheet which I have also done.
Some thoughts on the kevlar long underwear
1. The motorcycle underwear is a loose weave that looks nothing like standard kevlar, it is yellow and flexes just fine. Basically the same as wearing regular long underwear in terms of bulk and comfort.
2. An informal test with a ski edge failed. If I pulled very hard I could get it to cut. For that reason, I won't suggest them. They were less than $200
https://www.webbikeworld.com/draggin-liners-review/, I don't think they are made anymore.
I got on sale last year's POC baselayer: 2020 POC Cut Resistant Base Layer Pant × 1. I'll probably wear both layers. The POCs seem totally comfortable and flex fine, hopefully they breathe. They size small, I got XL and I'd guess they were on the small side of a large.
I definitely have a different risk profile than alpine skiers so that probably makes a big difference.
thanks
Breck