I have a lot of tex-Mex players where I am and I get at least 2-3 broken reeds a week, more if the weather is good or there is a holiday.
It is a bit of a problem to stock all the diatonic combinations that are possible and I often have to make pairs out of regular accordion reeds.
Example, I had a guy who came in today with one that had HM reeds in a pitch I did not have (g/a) I had no HM reeds even near that setting so I used a nice 1950's HF in g# and hand lap ground it up to G on one side and down to C on the other while maintaining the surface curve on the reed.
This took about 15 min total.
The profile grind on the old reed (out of a recent Hohner ) was pretty un impressive and nowhere near as nice as the one I used before I started.
I told the customer that I did not have the HM reed and if he ordered one I would swap it out when he got it for free. He is a really good player but neither of us could tell the difference between it and the next reed. the HM reed was slightly longer so it would possibly have a faster response that the one used but I could not tell in this case.
I have hand made and riveted in reeds on bandoneons on occasion.this takes about an hr to do one reed. There are tons of reed shapes and profiles and lengths so stocking individual reeds would be pretty much impossible.
A additional problem is the rivet hole which is not any sort of standard diameter.
I think with the heavy vibrato of Tex-Mex boxes the tonal advantages of hand made reeds are kinda buried.
I can't say that the HM reeds are much more break resistant than others , but in theory they should be a little better as the grain of the steel makes a difference on the reed valves in some pulse jets I have worked on, but the reason those break is more about the violent valve closing action.
Smythe's Accordion Center, since 1997