What do you see as the downside of tubes?


I have decided on getting a tube amp and it will be the integrated Mastersound 300B driving a pair of Living Voice Avatars, so at least that decision has been taken.

My main question is what you see as downsides of having a tube amp. As I've decided on getting an integrated tube it's really about what the downsides are I might want to know about beforehand.

The ones I'm aware are the following.

-The tubes need to be replaced and in the case of a 300B this will be somewhat costly.

-Bias is another issue but I'm not sure how big an issue. Do you plug in your meter every so often or just when you roll tubes or replace a dead one? The meter as such isn't gonna be a big issue as I don't think it's that expensive.

-Heat won't be a big issue as we have no kids nor a nosy dog that could get burned. Hope my electricity bill isn't gonna go through the roof, but then again, I can't quite imagine that.

I'd appreciate if you could add whatever your experiences are regarding this question are as I'd like to know more before I buy it.

Thanks
krauti
Raquel's original comment had me somewhat baffled; the follow up post clarified things. A 4 ohm load is harder to drive and to do it properly does require more from an amp. That's not the case with a more efficient load. A properly matched system can work well with a "lesser" amp in a well matched system, though at some point a matter of "degrees" will creep into any discussion of audio equipment.

Unsound makes some interesting points. In my limited experience there's validity to them all, but, again, it comes down to matching equipment. But Unsound also makes the best argument of ALL for tubes, albeit indirectly. They keep life exciting! Taking my Seedwings Sensor (Google it) out most weekends isn't enough. I need the excitement of tubes, too! :-)
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my twin boys grew up with big tube amps sitting on the floor, wide open without cage. no, they never got burn.

my friend puts it best. if you can train a tiger to perform in circus, you can train your kids not to touch the tubes.
The only time I had a tube amp damage a driver in loudspeakers was from a cheap poorly built dared amp that had parts shift in case work. Have had tubes fail never had 1 damage any amps or loudspeakers. Mostly you hear noise and slightly more distortion that lets you know its time to check or change out tubes. Realy not a issue. 300b available from $150 pair up. The mastersound can be retubed from about $250 up. I have had solid state amps damage loudspeakers when they have had problems this is not just a issue for tube amps.
Mapman; I have a b&k 747 tube tester and check tubes every 6 months. I think visual and audible changes are a indication as well to check tubes.
Also I kept a bias adjustment log when I had amps with manual bias adjustments; When bias starting to drift I would pay closer attention to that output tube.
I know many people will think this is extra work but I have several $$$ invested in my amps and pre amp and just want to keep them running at their very best;much like a person who maintains their car.