I'm nowhere close to an expert, but I've never heard of steady state, maybe it's a nickname for solid state? Or like what
@ConfoundedBridg I think said, possibly a state the amp can attain.
I've had tube amps be real reliable, even when pushing them so hard and gigging regularly. I've heard the issues too, though. I think it's the cost of maintenance when it does occur that'll be a factor. Kinda like comparing a BMW to a Toyota. Both reliable, Toyota may be slightly more so, but repairs for the BMW will likely be more expensive. This is just speaking in stereotypes, no specific preference personally.
I totally agree with @br1qbat and a lot of the others, there's great amps of every technology type. Weight for sure can be a factor, though Mesa and Traynor both have 200+ watt tube amps that weigh in at or less than a lot of AB "lead sleds." I think in the 40-50lbs range.
If you're open to the price point you mentioned, check out the Mesa TT 800. Supposedly very tube like more vintage voiced on one channel with power amp distortion emulation (on both channels), and a very clean more modern voiced 2nd channel. Mesa is reliable, but more than anything, seems to go out of their way to service their customers.
There's a lot of great amps within that cost range too. Most already mentioned. Ashdown ABM Evo series would be another I'd toss in the ring. 500w would likely be plenty, unless you want immense clean headroom. Sounds like you're in the right direction as a whole though.