You and I have already discussed this in person, Peter! Ignoring the previously mentioned benefits of saving weight and space, here's my two penn'orth:
I've had a few vintage amplifiers and I will always love the sound. However, like Robbo, amps are only for use with a band now, for me. Valve amps have a sweet spot which is never in the quieter ranges. I find I often need to drive an amp too hard for the size of the room, or otherwise feel like I'm not getting the full benefit of the amp. Then, as Dave says, you have to consider the backing track, which needs to be loud enough to compete with the sound of the amp (which, of course, needs to be miked to get a satisfactory spread). As a result my gigs used to be way too loud.
Like you, Peter, as you know, I'm using a Joyo. When I stopped using vintage gear on gigs I fully expected to receive less compliments on my sound, but I was wrong. People still gush over it. I do hear ways I want to improve my sound (entirely reliant on budget), but the AC Tone is in no way a weak link for me. It's superb. Nowadays I need little-to-no sound check other than simply making sure the PA master volume level is right! I even find it easy, when using distortion, to get good amp-style feedback when required.
I used to spend an hour constructing my most basic rig. The extra equipment needed simply to facilitate the use of an amp? One extra guitar cable, a mic on the amp, an extra mic lead and a small mic stand. You have to position the amp to get the visual right. Then the amp mic (SM57 for me) needs to be sound-checked in isolation merely to get the position on the speaker cone correct to capture the right tone. All extra cables then need to be coiled/tidied for presentation once connected. That all takes a lot of time. Thanks to modern technology, including my AC Tone, a column line-array PA, and an old mobile phone for backing tracks, my record set-up time
for my whole rig is now six minutes. In the past this simple gear has allowed me to play one care home session and two pub gigs in a day, with very little time spent concerning myself with equipment.
For me the overall show is far more important than showing off gear and faffing over equipment settings. No matter how much I didn't want to believe it when I was younger, the audience doesn't care what amp or echo I'm using. I wish I'd listened to the people who told me as much years ago. My anorak ego wouldn't let me listen. There are way too many guitarists with colossal egos who fawn over their own gear and/or love to haul huge, expensive rigs with them. Nah. Audience interaction, likeability and setlist structure/flow are infinitely more important. A clean stage with some simple (or not!) lighting, with as little as possible equipment cluttering the performance space makes for a far more impressive visual than any guitar amp, no matter how pretty your own gear might look to you. The impression I once gave my audiences was 'equipment geek'. Now my focus is on fluency of the show and a simple stage presentation; my jacket offset, on my general guitar gigs, by a pair of jeans and aged Beatle boots, just to make it look as though I'm not trying too hard.
Sorry, I digress...
Basically, get on with the music as simply as possible and make your life easy. Modern technology means all the sounds are there for you.