@mickrich - thanks for your work on these profiles. I am late to the party on these but I like what I'm hearing.
Just on ribbons - frequency balance for dynamics and ribbons particularly is strongly influenced by the "proximity effect" - eg put many mics straight in front of your mouth and a few millimeters away --> you get loads of extra bass and come across like Darth Vader. As you back it away, the bass boost is attenuated and you get a more balanced sound. Of course your mic pre or mixer channel may offer bass rolloff or other Eq options.
Same goes with speaker cabs, close micing with a ribbon or 57 will be much bassier than the sound a few more inches away. As you back further and further away - some of the Jazz oriented profiles on RE were done from 1.2 meters - it will get darker in most rooms as the balance between direct sound and reflected sound tilts toward the latter.
Close micing - right on the grille can be necessary for isolation - eg live on stage or in a studio with multiple musicians spilling onto your guitar mic - but in a situation where a guitar part is being recorded as an overdub or a solo track, the mics can be anywhere that sounds good - depends on the amp, room and what you're going for. The sound we all like from an album could have been obtained with no close mics at all. Eg - the recent discussion here on the guitar riff sound on the Money for Nothing session at AIR studios which was a complete accident - stray mics pointed at the floor etc. No engineers were involved