I would be interested to learn more about the design process that UM uses. Supposedly they test things to see what works and what doesn't, which is why they don't offer driver upgrades for just any IEM. But I still doubt that they spend as much time engineering things than say Westone, UE, JH, Livewires, etc. These other companies spend a lot of time on design, armature selection, tweaking each sound tube to be the proper length, etc. I wonder how that translates to real world results.
It makes me think of regular speaker design. Many people/companies can source a decent speaker enclosure, and drivers, design a passable Xover, throw them together and end up with a pretty good sounding speaker. What seperates them from the elite speaker designers is attention to detail. Someone like Danny Richie has extensive experience designing world class Xovers, pairing them with the perfect driver, and assembling excellent enclosures for them. He has certainly tried many things only to find that an improvement was impossible in this or that area. Hopefully that sort of thing is taking place at the custom IEM companies, which is what justifies their somewhat premium price compared to some lab in China.
EDIT Upon reading this, it seems hostile. I do not mean to imply anything bad about UM. I have talked to Sam and he is an extremely nice and knowledgable person. I have no experience with their products, I am simply wondering what resources they use for their work. I doubt we will ever know unless someone from there posts here one one of you who lives locally gets a tour.