Modern tube amps are a lot more rugged than one might think, and one of the nice things about 'em is if after thousands of hours of use a tube gets old, you simply replace it. Also, I seriously doubt that any harm comes from hitting the re-bias setting more often...although as Bigshutterbug said, it's simply unnecessary. I bought a voltmeter even though I don't really need it (I use an "ez bias" amp with LED indicaters) just because it's interesting.
A note on tube amps...I dragged a couple of Fender Twin Reverb amps around during most of the 70's (4 6L6 tubes facing so all the heat goes up into the chassis!), as well as using a really old white Bandmaster, A Mesa Boogie Mark 1, a Marshall combo, etc., and they always sounded great and were extremely reliable. I mean extremely! I currently use a 6V6 based "boutique" all tube combo daily now and if you think about the vibration and heat those things suffer, you sort of get the point. I realize hi end home audio amps are a different animal (less beer spilled on them usually, and baggage handlers don't drop them as much), but not that different really.
A note on tube amps...I dragged a couple of Fender Twin Reverb amps around during most of the 70's (4 6L6 tubes facing so all the heat goes up into the chassis!), as well as using a really old white Bandmaster, A Mesa Boogie Mark 1, a Marshall combo, etc., and they always sounded great and were extremely reliable. I mean extremely! I currently use a 6V6 based "boutique" all tube combo daily now and if you think about the vibration and heat those things suffer, you sort of get the point. I realize hi end home audio amps are a different animal (less beer spilled on them usually, and baggage handlers don't drop them as much), but not that different really.