... I'm thinking what is the difference between closer to mic and less gain versus further from mic and more gain assuming It generated the same signal level . My first instinct is noise . But then I guess it's going to capture in a different way too. Too much physics for my head . Try it and see i think is what I'll do
Well, there are a couple of significant differences.
The first is that when you move away from the guitar, you pick up more of the entire instrument. If you are 10" off the neck joint, even with a fairly loose pattern cardioid, you're just going to get more of the top part of the guitar and [probably some] string noise, and a bit less of the lower bout than if you are even 18" away.
With the larger distance, though, you now are capturing more of the room because its "input" is then simply louder in relation to the amount of energy from the guitar that reaches the mic. If your room is very dead, it might not matter for some things, but it's likely going to be there, as well as some other sounds like your chair or foot shuffling, that you might have been able to ignore when close micing.
I don't mean to imply that the farther distance is worse, because if the room sounds good, it's probably going to be a better, perhaps even more authentic capture, but you'll have to be more aware and really listen to what's happening, and you'll need to learn to be an even more careful player than when close mic'd, at least IME.