I can't see how the spigot is a non stressed area since the piston rides into the spigot area. The piston then dwells at the bottom like it does at the top when the rod reverses direction.

I know there are these builds out there, but I dont think that I will be using the stock cylinders if I end up going 106/107. I have to believe that S&S has earned their credibility over the last 52 years, and has done the testing to be able to make statements like they do here in print.
My biggest fear would be a cracked cylinder or an out of round condition which could be caused by over heating due to weather and traffic conditions.
I now leaning towards the the Axtell or S&S Jugs. The money spent on the after market cylinders above what it would have cost to bore a set of stock cylinders seems to be good peace of mind. Just like home owners insurance ... no one wants it, but sure glad you had it if you ever needed it.