From what the online demos sound like so far, I'm going to be totally blunt about it. The 5 is 1500 dollars, the 20 is 1800 dollars, and I wouldn't give a THIRD of that for either one of them. Seriously unimpressed. If you don't keep the bass turned all the way off and turn it up for some overdrive, they give exactly the kind of flabby, gritty, uncontrolled overdriven bass BLATT that I absolutely DESPISE.
Oh, I'm sure they're very well made since Mesa made them, but tonally I'm not hearing anything that piques my interest. They're OK, not great, not even particularly good. But I can see that some people who used to own a Falcon back in the day may be seeing this through their rose colored nostalgia glasses, and will buy it.
I DID own a Falcon. I inherited it from a friend who died and left me what was left over in his guitar amp repair shop. (He was the local amp guru, quite good at his craft, and a very good friend since about 1985.) I did have to complete repairs on it. I wasn't impressed with it, but I had a willing buyer, a local blues guy who likes a certain kind of gritty old school blues tone that is very much a niche thing. He has it still.
I see this as a needless, even pointless diversion of Mesa's manufacturing capacity in order to pursue somebody at Gibson's pet nostalgia project, diverting capacity from Mesa when they'd be much better served trying to get amps over to the UK and Europe where they're in extremely short supply and high demand.
For what they're asking I'm confident that I can find a lot of better sounding amps for the same money Gibson is charging for these two Falcons.