Corvair conversion engines

As my research continues, I have been investigating possible engines for
a 601XL. The Corvair engines looked like a good candidate. The reports
seemed very good and the engine was surprisingly inexpensive for initial
purchase and long-term maintenance.

The stated expected TBO is 1500 hours and the Corvair Authority website
documents the use of a Corvair engine in a 601XL.

Everything seemed OK until yesterday when I read the most recent updates
on their website. Seems that the "untreated" automotive cranks have
been cracking in a very short time. Nitriding seems like the only
solution. But with standard cranks cracking at under 100 hours, what
would be the expected life of a nitrided crank. Twice as long, four
times as long, eight times as long? This would still fall short of the
1500 hour TBO stated by the Corvair Authority.

Does anyone have any first hand experience with Corvair conversion
engines? Any info on their realistic life and reliability?

TIA,

CV