I know a guy who does exactly this (miked amps in front, tilted back to point at the guitarist's head) and it's about the best live guitar sound I've heard in a while. Anthony Krizan had multiple (at least 2, maybe 3) vintage amps in front of him with drummer's plexi-shields between them and FOH. It couldn't have been too loud, because he was using the house wedges (no IEMs) as monitors and his singing was spot on.It doesn't look as cool, and makes higher wattage amp choices impractical.
I learned it from a local semi-pro. I've never wanted to work with any guitarist as much as I wanted to work with this guy.