I bought a new 2015 from a dealership. Rode it for a few thousand miles, then raced it for two years in a local series in two classes. So a total of about 30 races.
So at the end of the last season, I had the engine taken apart to inspect it because it was down on power at the last race of 2018.
Wear on crank journals.
Wear on wrist pins.
Rods were out of spec with the large end of the rods slightly out of round. Very small measurements of thousands of an inch, but enough to hammer the wrist pins.
Bottom of pistons stretched where wrist pin goes through.
Bottom line, my 2015 engine was worn out. And I changed oil/filter every race, always on top of the maintenance.
Others have guessed that the crank problems reported may be a combination of over pressurizing cylinders, or timing that is too advanced, or local tracks that have a very long straight which is where some of the 2015 crank breakage issues seem to show up. But it is clear that the oil passage design is an issue, but here in colorado the elevation is so high we never saw one break.
Note that in 2016 they added a thrust bearing the the crank to eliminate side-to-side slop and that helped, but in 2017 they changed the cases, crank, and even the valve springs now have two springs per valve (2017 on).
When I learned that my 2015 engine was done I said "no more silver motors for me" - meaning, no more 2015-2016 engines for me and I sold my backup bike.
I then purchased a salvaged 2017 engine with 500 miles, and I sent it to Gary Dean (crew chief for Kyle Wyman, former crew chief for Josh Herrin when he was on an R1). He is an expert R1 engine builder. He inspected it, said the engine was basically new, and we built it. Head work, and lots of other work. That was going to be my main bike for this year until I had an opportunity to get Bobby Fong's R1 from the Hudson MotoAmerica team. I bought that bike, pictured below, and I rebuilt the entire bike with new electronics and many other upgrades.
Through this experience, I have spoken with motoamerica team managers, and I have heard the following quotes that are interesting.
"all we have ever run in motoamerica is silver motors, and we have never had one go" - Westby Team
"we have never seen a silver R1 engine blow up in MotoAmerica" - westby team.
"titanium con rods are only good for about 3000 racing miles and then they are done" - literally 3 teams and a tuner all told me the same thing, which I witnessed with my engine teardown. The rods are fine for street use, but 3000+ miles of racing and they are done.
The 2020-2021 R1 will be all new, and will be revealed in July at the Suzuka 8 hour. It has been seen in the wild. Hopefully some of the crank issues will be resolved in the new design, as the motor will be all new.
Hope that helps.