Not to be overly negative but now that I've seen its price, I'm very skeptical about its preamps, quality of headphone amplifiers, converters, etc.
If they made a high end version of this, I'd be VERY interested.
You raise a good point. In the context of you get what you pay for. Of course some products fall into getting what one may not need. But keeping things in perspective, quality of preamp, routing, headphone amps, amp type i.e. A, B, AB, etc, converters, in/outs, and such. Quality will largely cost more. Then one has to weigh and choose relevant needs. YT bloggers such as Julian Kraus provide the best audio interface comparisons, because his testing has a consistent criteria and is indeed thorough. One can then make their own decision far better than what is simply new, or hyped as what 'might' be deemed superior. In the end, the better stuff usually shines with the overall industry approval. Only, it takes some digging to know what that is. Not all manufacturers come up with the best designs (whatever that might be), but instead meet limited budgets, or allowances. So compromises are abound.
That is with any industry. Remember when Infinity made excellent yet cost effective hi-fi audiophile speakers? Only at some point, they scaled down to mundane department store speakers. Remember Famous Amos Cookies? Only to end up with basic ingredient bland bleach flour chocolate. Chip cookies.
Remember SSL (still building high end consoles), but make a very compromised so so audio interfaces. The list goes on. Like anything, some do it better than others.
When Julian tests this and grades the Flex-10's performance, we'll have a good idea. But if the buyer is happy with the product, and uses it with satisfied succes, that is important.