If one's willing to build a carbon dropbar monster cross, "a lot of the hardtails" becomes pretty "a few". The problem is the seat tube length, which is short in size S almost everywhere. Probably alu/steel/titan are less concerning in this case. Flatbar (your actual frame size) is no problem.

There's a story about the EDGE wheelset.
They originally claimed 120kg max weight and pressure up to 120psi. A guy bought them from alix exactly because of those specs. Yes, he double-checked with the shop about the working pressure (90-120psi), and they confirmed it. According to them, some fancy light carbon was used that didn't compromise strength, ofc. And guess what, after a short while, running the specified high pressure, the rear wheel shattered during a ride (yeah, delamination thing).
Elitewheels fuqed around for some time with classic: "please close the dispute friend, we will send (or already sent) a new replacement friend, trust me bro and close the dispute". Eventually, alix stepped in and asked for a formal diagnostic certificate from a workshop to confirm it was unrideable. The guy did the stuff, sent the docs and got a full refund.
Happy end! Kind of.
PS: the dispute took three months.

You can ask them to add/remove whatever mounts you want for 10 USD/pair. I added 2 on the top tube and removed ones on the down tube (near the bottom bracket). Gotta pay 20 USD extra.

concerned about durability

Yeah, been there. My first random wheelset from aliX with similar rim specs and weight (about 450-460g) served me quite well in big mountains: a month in a bike park, half on local trails (still big mountains) and another half (or slightly more) on rocky hills. But I ran inserts. Now realized, that it was probably overkill and my next options will be around 420-430g. I'm 70kg naked weight, so if you're not fat big, they're gonna serve you well on harsh terrain (with inserts at least).

And, good to hear that they offer different hubs. It's a bit difficult to find a supplier who does that. I guess I'll go with them next time. So far I chose DFS and their THR hubs. From my understanding, they can build whatever weight you want for a certain rim geo. Although, my wheels will be delivered later on, so no feedback yet.

They are sourcing hubs neither from THR nor from H-works. They offer whatever in-house hubs (with ratchet) or dt swiss. Zero details. Any questions about schematics/replacement/compatibility were ignored.

The lightcarbon quality is kinda questionable.
I got the LCFS958, which I use from time to time. Yes, it's rideable (in a bike park), it does not disintegrate and will likely hold for a while. But the quality of pivot mounts and bearing seats is average and below: there're plenty of cavities/porosity/signs of delamination. I made a mistake when I didn't check everything on arrival and only took a good look one month after the end of the warranty during bearings replacement (yeah I rode the bike quite rarely on vacations).
Another thing to remember is the warranty: it counts from the date specified in the invoice (that excel sheet with the quote you got from them). All the time required to get the frame built/painted/shipped is included within the warranty period, so you can confidently remove these few months from coverage once you get the frame.

Would I buy anything from lightcarbon ever again? Absolutely not. Would recommend? Certainly not.
560 bucks frame + 140 shipping + VAT was probably an okayish deal back in 2021, but still have a feeling (in a bad way) that I bought something from aliexpress on sale. Looking now at their frame design, my experience and others' (check the road bike section), I will stick with another supplier (which I did, actually).

So, a new guy in the first message advertising a new store (less than a month fresh) with zero rating/feedback and the only crankset available with an inadequately low price for the carbon+titan combination? I guess nothing's wrong here, let's buy, everyone, right?