Well designed tube equipment should not sound substantially different that well designed solid state equipment. That is assuming the designer is trying to produce a neutral sounding product. I have had a number of different pieces of tube equipment (Sonic Frontiers, Audio Research, Counterpoint, Moscode and Quicksilver) and some are low maintenance and some definitely not. My advice is not to buy a preamp because it has tubes, but to buy a great sounding preamp regardless of whether it glows in the dark. Once you have narrowed down your choices, do another post asking for reliability feedback for that specific product.
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?