I've got a stereo amp, the Vox AD120VT. Original, blue cloth version with the big 2x12 box. Same size / form factor as an AC30.
The stereo effect is surprisingly pronounced despite the speakers being so close together. It does have the advantage of convenience - one box, not two. There's also consistent balance across the two channels - though obviously if you want a deliberate effect of two very different sounds, then two amps is still your birdy. For recording, as you note, there'd be no difference - it's all about mixing the channels. Live, if you're going through a PA would be much the same - even miking, just mic up the two speakers separately.
For the most part, it makes little odds to me - I don't care about the sort of effects that benefit from the stereo function - indeed, at some point I'm going to sell the Vox on because I prefer a much simpler amp, and I barely use the vast majority of its functionality, just set it two Twin Reverb mode and dial in a little break-up.... it's wasted one me.