Update to my update:
Vipassana,
Thanks for the tip on the rivnuts. I ordered a tool from amazon and m5 inserts. Will try crimping in new rivnuts. Right now I am running only one bottle cage. That's not going to work in a race.
A cure for the frame creaking has remained elusive... I have tried synthetic axle grease and silicone grease. None have worked. My next thing to try is some kind of elastomer. I did fix the creaking BB bearing. See photo below. One bearing was nearly frozen. Not surprising since I found enough dirt in there to host a reasonably sized flower bed.
I have tried several cable slap fixes. They all work for a time but eventually shift around and I end up with slap. A deadened slap, but still a slap.
Last weekend I installed new brake pads, SwissStop Sintered. The Disc E pads worked great until I burned through them. The rear pad was nearly completely gone. I have been riding with very little braking power the past few weeks. The Sintered pads have phenomenal power. I am now loving the XTRs again.
Unfortunately, during that first ride with new pads I had a little crash and that crash somehow pushed the front brake lever all the way forward, ejecting the snap ring out of its groove which holds the piston that applies pressure to the master cylinder. The brakes still worked, the lever just wouldn't return to it relaxed position flipping several inches forward when released. I thought the lever was toast since I couldn't find any repair instructions on the web. After digging into the mechanics of the mechanism the repair was completed rather quickly using a pair of snap ring pliers, after draining the system of fluid. A quick bleed and they were good as new.
I am still on course to buy the Niner AIR 9 RDO, but I am likely to wait for the right deal to come along. The frame retails for $2k. I would like to find a close out or new frame purchased second hand locally. There's a 2015 frame for sale on Craiglist for $1300, I would buy it but unfortunately, it's an XL.
Regarding the alleged conspiracy among bike manufactures to sucker us cyclists out of our hard money through continual revisions to "standards" and geometry, I say, you might have a point, but it's really a myopic allegation, IMO.
No one forces you to pay full retail every year to buy the latest and greatest gear. Great deals can be found buying closeouts on last years gear or prior generation components. If you are resourceful there are great deals to be found on state of the art gear. The reason why bikes have become so good over the past two decade, MtBs in particular, is through the hard efforts of the big name bike manufactures. Effort which requires tremendous capital which must be recuperated. Yes their business models demands they must continuously evolve and innovate. Specialized moto is "Innovate or Die". I think that credo applies to all bike companies. It's a highly competitive market. To stay in business you must push at the margins of technology. And yes sometimes that means changing standards. Consumers vote with their wallets. I refuse to take the cynical view by dismissing it as change for the sake of change.
The reason why relatively inexpensive Chinese frames exist is because of the hard work done by the name brand bike manufactures. I have yet to find any Chinese bike manufacture producing original innovative designs. They are blatant copies of existing bikes. Hence their low cost, since they have little R&D to recoup, and low overhead, and cheap labor, and can skimp on quality control.
Ultimately, I say ride what you want. Build what you want. But don't hate on the name brands because they are the source of the great equipment we get to enjoy, either directly or indirectly.
Photos of mentioned mechanical repairs and racing photos of the 256-SL in action included below.