A few observations of my own:
1) Manufacturers generally do not care to build products that vastly out live the warranty period. Its not cost effective, and most coils (COP) will last 30K miles no prob.
2) At least with GM, the highest performance models of the LS series motors still use CNP do they not?
3) I never meant to imply heat is the only killer of COP setups. But I do believe that run side by side in the exact same setup (i.e. two YZ450's one with COP and one with CNP) that the COP will fail first, even if it lives 10 years before doing so, just as a comparison.
What is the leading cause of an ignition coil falure?
1) Most manufacturers do want these items "serviceable" so that a tune up feels like a tune up. That is the opposite approach we are taking. What we want is a reliable lifespan and high output which is a bit more difficult to accomplish.
2) Yes, but we must also consider that the LS engine is based off of a 50 year old design using pushrods (btw I'm not knocking the engine, it is well designed) There isn't enough room to use COP so they use CNP (coil near cylinder) which uses one coil per cylinder. Keep in mind their latest V8 designs (Northstar V8's) use COP and all other engines use COP as well. I'm sure the time will come when GM redesigns and goes to direct COP as well since the new Ford engines are outpowering them and have greater fuel mileage. It is, IMHO, inevitable.
3) You are right. The COP setup does have a harsher operating environment but it's always at the cost of performance. Ignition wires also introduce another component that can cause issues or poor running if oxidation, flashover, etc. set in. I'm not knocking either design, as long as they are made to last and withstand the abuse both can function fine.
Forgot to mention, the leading cause of failure is because of poor design of the insulators and placement of parts in relation to other components.
In the end, all aftermarket components are out to do one thing. Find the area where to OE parts could use some refinement and make them better. We did the same thing in the ignition systems where we found issues but corrected several potential issues and made a higher power unit for many platforms.
As can be seen the newest CRF450 already moved to a new remote mount unit as with the YZF450. It's because of all the hampering problems in the past.. but in doing that.. they made new problems which we also fixed.