You can inspect the interior of a miflex (or any hose) with an endoscope. They can be had for $17 on Amazon.
The one I got was $60 because it produces a slightly better than 1080p image.
I got it for other things (like looking in my tank) but it works perfect for hose interiors too.
The lack of ability to inspect a miflex with the naked eye is the reason for the finite lifespan. Rubber hoses also have a finite lifespan. The difference is that it's much easier to tell when you need to replace it. You might be able to get 10 or 15 years from your miflex hose just like you get from your rubber hose. The manufacturer set a guideline that will guarantee they can't be sued unless the hose is truly defective...like any manufacturer in this sue-happy world should.
@wbatten1 What company are you with? You mention "your" hoses and that they're better than miflex or rubber hoses. Don't keep us in supsense!
I don't think much of the coated tech miflex hoses myself. Although since I don't use miflex for long hoses, chafing is a non-issue.