In regards to muscle memory I find it quite fascinating in humans. I've not played my guitar for a while, certainly not during the summer months, so I ask myself will I need my music book, but I'm not very good at playing and reading. Or will I will just remember what I know (my memory is shhite), and the answer for me is just put your fingers in the correct sections of the frets for a particular song and your hand/finger memory brings it all back with the aid of your hearing. It's a bit like typing on a computer keyboard, you instinctly know where the letters are without any looking and without following any set form of fingers to keys. Just routine, habit, established over time.
I'll get back into it again now the Autumn/Winter months are drawing in. Goodluck with your purchase.
Although there is one problem, I've got a new laptop and the full stop/delete button must be in a different place because it keeps fooking me up, not sure what it is but something in the number keypad area.