Bridging two SS stereo amplifiers to mono is usually NOT a good trade-off for the massive power gained - up to 4x power for amps that "double down" i.e. high current. Why 4x power and not 2x? Because bridging doubles the output voltage which also draws (or attempts to) 2x current since the speaker load is the same. Or put another way, each L/R side of an amp "sees" half the speaker load and thus is dumping 2x the current at the same voltage as before - but both sides are now working in tandem (opposite phase) so these stack and 2x (current) * 2x (L/R sides) = 4x. Net result: amp is working harder (as if the speaker load were halved), and it often sounds worse. There’s also often extra circuitry to invert the input signal for opposing phases. I’ve experienced this myself - don’t like the bridged mono sound. Dedicated monos are the much, much better way to go.
Tube amps with a switch to stereo/mono mode are different - they typically parallel the output of L/R sides through their output transformers. The taps effectively become half the labeled value in "mono" mode (e.g. 8 ohm taps become 4 ohms), so you just move down to the next tap as needed - that’s how 2 ohm taps (or even 1 ohms) can come in handy! In my experience, the extra power here (2x) is a benefit with none of the downsides of bridging - in fact, often these tube amps sound drastically better in mono!