I agree with that philosophy, my wife wanted me to change out water heaters just because ours was getting old but I wouldn't., thats been several years back and the water heater is still working today.
I have 400 hours on my 422. It is about 4 years old. I replaced one hose. It broke when I dropped something sharp and heavy on it. The other hoses look dirty, but in good conditon.
30 hours on my PT425 and I've already replaced one hose. Only thing is it was the flex hose on my grease gun. I laid the gun down momentarily on the rear tire and the hose flopped onto the muffler. Like an idiot I forgot the machine had just been run so I had instant rubbery goo on the muffler. However, a couple of hours of running later and the muffler was clean as new - kind of like a self-cleaning oven.