the two present the likelihood more are out there and lack of more confirmation doesn't prove anything. i based my commentary on this lock issue on my experience. i didn't realize Mikhail changed the fasteners he uses and currentyly uses.
with respect to the upgrades i had been asked what's my "beef" and that's just one of the four or so issues i don't like. though, each person has a right to their own. it wasn't my intention to make it like Mikhail is doing anything wrong, he has the right to charge whatever especially if he's got people willing to pay. and yes, he is very good at selling the upgrades, which i don't fault him for either, but imho value for ones' dollar is not best served especially getting into the $5K to $20K range for a headphone amp.