After fifty years of pursuing the high end… the first forty with solid state amps.. I will not go back to solid state. I found that tube amps can be incredibly reliable and more importantly musical.
When I was working I put about 600 hours a year on my system. That would require retubing about every five years.
I now listen a lot more and have replaced four tubes in the last three years, one DOA and three at normal maintenance time.