A study measured a large number of used IPPs. The LGX lasted an average of 29 months the CX lasted 39 months and the Titan 48 months. The LGX grew in length twice as fast as all the others. Apparently all IPPs stretch. Before everyone gets excited. The LGX only grew an average of 1/64 of an inch per month. So 1/4 inch every 16 months. The others grew 1/4 inch every 32 months on average.
More than 1750 used LGX cylinders were included. Titans were the lowest number of cylinders included. Obviously that is because A the LGX is much more popular and B the Titan lasts on average nearly twice as long. I posted the url last year I think don't have it anymore.
Hope this helps.
Is this the post that has the link you mention?