I don't have a CDI motor and probably never will, but to the issue of RF noise and spikes, I can speak from industrial experience. Each component in the circuit with these spikes is seeing them every time they happen.

The best analogy I've heard for RFI degrading electronics is: I can poke you with a pin and you say ouch and move on. I poke you again same result..no pin ***** is gonna kill you right? Now I poke you with a pin billions of times. what happens?...you could easily die....

Same with RFI, the effect is cumulative and it's only a matter of time. Each spike stresses components unitil the weakest component gives up.

Again from industrial experience, we can never predict the effects of RFI on any particular system or component with certainty, and as a result must adopt the "best odds" approach to system design to maximize our average time to failure. You will either need to overdesign the components to ensure that they last for the intended life span (which I doubt any RX manufacturer is doing) or provide isolation. In this case, it would seem that isolation looks pretty good.

Richard

Editted-Apparently I the word I picked in place of "poke" is not acceptable in any context...