In addition to AV work, I have also worked as a boat mechanic, trained in EFI, Multi-port injection, fuel systems and other areas of diagnostics, repair, setup, and the electrical side of it- after working on literally thousands of boats, I think I'm 'mechanically-minded' and the repairs ranged from assembly/component replacement to full tear-down of engines like Ford 351 and Chevy Corvette LT-1. I have rarely had leftover parts when finishing the work.
When I wrote that I compared it with another chain, they were hanging and if I didn't have the specialty tools, I bought them- not a fan of "I can get this to work" unless it's something like a hex nut/bolt. Also, comparing it with another part implies that the reference is within spec, and a quality gauge can remain 'in spec' as long as the reference chain isn't used on a bike. WRT sealed vs loose or caged bearings, sealed are usually more precise and because they don't allow that crap to enter, they last far longer. Yes, the BB is square taper, but as I wrote originally, the BB bearing is sealed and the bike is from 2001-2004, so a lot has changed since then. My Trek road bike's BB is a caged bearing, but that one is from 1984. I'm surprised sealed bearings took so long to be used for axles- zero adjustment and no need for someone to know how to set the preload.
I think a lot of people go for better components even though it will make zero difference in how well the bike will perform. Sure, a ceramic bearing can be 'better', but to what degree does it matter? If a caged headset bearing's friction is unnoticeable as it moves through the usual range (while riding) of maybe ±45 degrees, what's the point? Same for any other assembly that's relatively well-sealed from the elements- compared to what is needed to make it rotate, anything we or the road/path are doing to it is brute force. If a bearing assembly lasts for 30 years and its friction isn't noticeable to anything but a strain gauge (certainly won't be measurable using a torque wrench), doesn't that mean it's 'good enough for all practical purposes'? It's very similar to using a $300 power cord when the OEM part is definitely adequate- this isn't something that needs to meet ISO 9001 standards.
But bearings are about more than just lasting for 30 years and using less energy to move them- they need to be able to withstand a lot of shock and resist wear, so the purchase/use of better ones is a much better decision than just using price/longevity as a reason for not stepping up in quality.
I have read some of the debate about various bike lubes and for anything sealed, I'm not sure it will make much difference, especially when the bike is going to be regularly maintained. The chain, OTOH, needs to be able to shed the dust, mud and other abrasive contaminants in order to avoid grinding the chainring(s) and the chain, itself.
OTOH, I am definitely a fan of extreme precision and accuracy- I have always been fascinated by mechanical assemblies and one of the things I like most about working in AV and boats is looking for solutions to problems that were considered 'unsolvable' by others. When I hear "They said it can't be repaired" or "They can't find the cause of the problem", well, I just call that 'good, clean fun'.