Could a semi-hollow body achieve the same sounds as an acoustic, or rather, could one be used as a near perfect substitute when played unplugged?
no. well, not really.
well it depends...mine still sounds like an electric, but im sure if it has a peizo pickup in it or an acoustic sim them sure. Unplugged its much quieter than an acoustic but might still be good
Would you say it's loud enough for busking?
without an amp, definate no
You could do it with a full hollowbody, but the center block in most semi-hollows really dampen it.