Self insuring versus third party insurance

I did a cost comparison of my overhaul cost (adjusting for cost-of-money) versus Pratt and Whitney's ESP (power by the hour) program.

The ESP Gold rate (includes life limited components and engine removal and re-installation) for my engine is about $155 per hour (that is the 2012 PT6A-67P rate - could not find the 67B rate). To do the analysis completely correctly, I would need to find either a 2008 (when I bought the plane) or 2004 (when the plane was new) ESP rate, but I could not find a rate sheet that old. Perhaps use $130 per hour as a ballpark estimate for a 2004-2008 ESP rate?

Not sure if that ESP rates cover "upgrades" like replacing the PT2 turbine early and the new rather than overhaul FCU or not. Also not sure if it covers overhaul related items (engine mounts, oil cooler overhaul, etc.).

Assuming it covers all of that (which I doubt), my cost including a 4% return on my money is about $93 per hour assuming 290 hours per year (12 years until overhaul).  In other words, if I had deposited $93 per hour into an account earning 4% after tax over 12 years, that account would have had enough to cover this full process.  

If ESP does not cover the service center overhaul related items (except engine removal and re-installation) or the optional "campaign" upgrades, my time value of money adjusted cost would be about $80 per hour.  If you want to include the rental engine (just the removal and re-installation cost since the hourly rate is about what a reserve on your own engine would cost), add $2 per hour.

So, something around $90 per hour (time value of money adjusted) to self-insure versus around $130 per hour to insure via Pratt. Guess I understand now why very few PT6s are on ESP.