Well, I found a cheap Fender Champion 50XL (160€ shipped) and got it to make tests.
I'm not interested in the amps pre, or its digital modelling either. I just want it as a power amp and real guitar speaker for stage monitoring with my modeller.
Power seems enough for stage monitoring. It's a 50W class D amp, and the speaker is a Celestion Midnight 60. It weighs approx 9kg.
Made some NAM captures of the preamp of my Mesa Boogie Studio .22+ and played them direct into the aux-in of the 50XL. A little care with levels, since the aux-in has no master control, it's always max power...
And the result is fantastic, so far. Just some EQ to mimic the Boogie built-in five band EQ, and there We go. Maybe it's too early to say it, but at least at home levels, this setup is absolutely great. It feels like my amp, it's approx half the weight, and it's really cheap.
It's loud. If you feed the 50XL with a healthy signal from the modeller, it can get really monstrous. And it still has some improvement margin. The speaker is decently efficient (96 dB) and lightweight (2.5 kg). But with a neo speaker, like a Jensen Tornado, you can even go louder (98.5 dB efficiency) and lighter (2 kg).
For the moment, I'm not feeling the need to upgrade the stock parts. I feel it's lightweight and loud enough.
I think this way of amplifying modellers is really interesting!