Try the side-by-side thing suggested above. It should reveal the differences between the products. Although my personal experience with that brand is not positive regarding transparency and accuracy of reproducing the recorded information, you will figure it out IN YOUR ROOM. Best way, and most of all, enjoy the music you like.
Re tubes wearing out VS solid state--they all have life cycles. If you listen 24/7/365, your tubes will have to be replaced occasionally, but the solid state will fail suddenly if it is typical. When? You just never know, but tubes typically have some MTBF rates published by the manufacturer in their specific model number.
Cheers!