I had DC 150, 150 a, 3- DC 300A, PSA2 and all of them needed to be serviced on regular 8 to 10 year intervals over a thirty year period. Caps of all types need to be replaced every 10 years or so and out puts changed. And when I sold them and traded them to Audio Classics the 300 A's didn't meat specs, so I took a hit. Well none of the amps met specs in fact. Mean while my old Mac amps are still plugging along after 47 years. The newer amps of course are just like new. (2-207's and a 206). When Crown was owned by the church all I had to pay for was shipping to the factory. They repaired them at no cost no matter the age and returned them at no charge. When Harmon took over the hand witing was on the wall, $$$$$$$$$$$, so that was the final push to return to an all Mac systems. Tri-amping and bi amping uses a lot of amps. Can you imagine having to find space for 10 7200's. I could get by with 5 7200's and 5 7100's. maybe 202's would take up less space, but I'm happy with what I have. I knew when the 7200 was introduced the Crowns had met their match and then some. But I was happy and monies were going toward two other pursuits, photography and RVing . But in 2008 I had retired and was home a lot more so I called Frank and we started updating my equipment and repairing units that were showing age.
The reason I got away from Mac amps in the first place was my woofers sound ed soft and Fuzzy as Frank Gow used to say with 2100's 2200's and 2255's. The Crown amps bi and then tri amping curred that though the midrange was a little hard and the highs on the brittle side. The 207 amp fixed everything down to 70 Hz or so. The bottom octave and half isn't as tight as with the Crowns but it is more musical.
I would think Bryston might give long term performance like Mac. I have only heard a few and they remind me of the BGW sound. I don't know about Threshold , Boulder and some of the others. Of the other brands friends of mine Haflers seem to hold up well. They're pushing 35 years without issues. Marantz amps depending on the vintage do well, too. I guess if I were flush with money I'd have 6 MC 3500's. Its really the only tube unit I would be willing to go thru the trials and tribulations of tube ownership with.