There are three insurance tales that are repeated from time to time in
various aviation forums:

1) If you own an experimental and don't power it with a certified engine,
you may not be able to find insurance. In the latest iteration of this
tale, the difficult to insure engines included Lyclones and rebuilt
Lycomings that were not "certified" rebuilds. Does anyone have first hand
experience with an insurance company refusing to write a policy (or
increasing the premium) because your airplane didn't have an FAA certified
engine? Let's leave the Subaru, Mazda, Ford, and other conversions out of
this discussion.

2) If an airplane (certified or experimental) crashes and all the paperwork
isn't up to date, the insurer will deny your claim.

3) If an airplane crashes with a pilot at the controls who isn't 100% within
FAA regs (i.e. out of date medical, taking benadryl, etc), the insurer will
deny your claim.

I don't believe any of these three tales, but I only have experience with
#1, and my insurer didn't have any qualms about insuring my airplane with a
Lycoming I rebuilt...

Again, I'm seeking first hand experience, not "A guy down at the field told
me he had a buddy who met a guy at Osh one time who...."