As a newcomer to tube world, I can only offer a limited perspective on your query. FWIW, to answer to your last question first, I suspect many of us attracted to tubes do enjoy being involved with the innards of our equipment. Tubes offer you the chance to "tune" the sound more to your liking. There are indeed sonic differences between tubes that are attributable to things other than the performance decline aging brings about. Comparing the brand new RAM labs tubes in my preamp with NOS Amperex does reveal diferences. The differences, to my ears, are not of the magnitude some listeners claim to experience. While the NOS sounds better, the RAM labs tested Sovteks sound pretty good. Life expectancy of tubes varies from design to design. Many Audible Illusions Modulus owners say they retube every 6-9 months, as this design drives tubes hard. Others may only require retubing every few years. Listen to some equipment and then decide.
To tube or not to tube...
I'm interested in upgrading my preamp and have been considering going to a tubed preamp coupled with SS power amp. I hesitate because of the reliability factor. You see, I grew up in the era of tube television sets, so it was a periodic chore to unplug all the tubes from the TV and haul 'em down to the local drugstore's tube tester. We'd wind up replacing a handful of tubes, and then be amazed at how much better the picture and sound was. A year later the drill would repeat. What's the situation with tubed preamps? I see a lot of discussion about trying this brand of tube or the other... I'm wondering how much of that "improvement" is due simply to replacement of weak tubes with fresh ones. What kind of life can one expect from the tubes in a tubed preamp? How much does the sound deteriorate over time as the tubes wear out? Are tubed preamps intended only for those who want and like to fiddle with the innards of their equipment?