Tom,
I apologize but I'm a little confused about what king of hoses you prefer. Sounds like rubber is out because they get so dirty. Is polyurethane the same as urethane? Am I clear to understand that you don't have a Flexzilla hose but are using their strain relief components on some other brand poly/urethane hoses?
If I've got that right are you recommending the polyu?/urethane hoses?
Again, I apologize for being a bit dense but I haven't used an air compressor for very long.
Mike