Hmm, well I tell you what... I hesitate to mention this because it could lead to some misunderstanding. But I will tell you anyway...
Carbon Steel can have a few different properties depending on how it is tempered, and this will have an effect on how thin it can be ground.
I find that "generally", if the steel rings long and loud when plucked, then it can be ground very thin and will be an excellent shaver. So though it is very hard, it is not brittle and wont micro-chip when honing or shaving, and on the other hand, it is not soft so it wont "buckle" and fold-over under the load of the whiskers when shaving. This is because it is tempered to “spring steel”. It will bend, but will not stretch and stay bent, nor will it brake easily when bent. I believe this may be one of the best (if not the best) type of steel for full hollow ground straight razors.
However if it does not ring or makes a short, "thunk" then it will not shave well when ground thin.
Also look for a slightly thicker ridge just behind the edge (every full hollow ground blade has one). The edge of course is thin, but after the bevel it a little thicker then gets thinner again, then gets thicker towards the spine... it's like an hour glass shape at the cross section... or some folks will say it has a 'spear" shape.... that ridge provides strength for the thin blade. Without this ridge the thin full hollow ground blade is almost useless.
The problems occur when guys like us attempt to restore razors while sanding or grinding remove tarnish, we get carried away and grind away the thicker ridge before you know it the blade gets really thin... it has happened to me a few times.
I would love to see a photo but... if you suspect the blade was restored recently then be cautious. But if you are sure it has not been touched then chances are she will be an excellent shaver... Look for the ridge and listen for the bell.
Having said that… this does NOT mean that ringing razors are absolutely the best razors, i have many razors that shave better than the best and they don't ring at all. But if the full hollow ground razor rings loudly, then there is a grater than 90% chance it will be an excellent shaver even though the blade is ground very thin.
Maybe one of these days Bart can make some audio recordings… then maybe we can find the “tone” that makes the shave.
Also you are correct, there is one down side, because it is flexible, you absolutely cannot hone with pressure or a couple of problems will show up
You may get a bad frown... or because the edge near the point has no support (it's a corner) the edge near the point will bend away from the surface of the hone more than the rest of the edge and you will be honing well behind the bevel making the point thinner than the rest of the edge... in that case the edge near the point will not get sharp.
It is long but I hope this answers your question my friend