of our own boat always uses a heavy industrial hose for the sanitation hose - I don't know the product name, however. Industrial hose is made for services much more trying than handling sewage without permiation so a visit to a good industrial hose specialist might provide an alternative (albeit a possibly more expensive one, I don't know). In our own case we have gone near on 12 years and the hose is still fine - we do though, always make a point of flushing
the hose clear after use of the toilet and if the boat is left for more than a couple of days we flush out the discharge side with fresh water
If ones boat is rigid enough, and any competently built cruising boat should be, then rigid PVC (even going to schedule 80) is the best solution by far, is easy to install with a wide range of fittings and valves and is what I am used to seeing in quality vessels. When the time comes to replace our own hose that is what I will be going for.