ok. as i said, i don't know anything about the ones which say gibson. I'd be extremely wary, but if you can try one first, then you're going to know more than me.
MIJ copies generally are great, but the big problem, as i'm sure philly q will agree with (he's a fan of them too), is that there is a wide range of models with a wide range of prices, and (assuming you're going second-hand) it's not always obvious which is which. You don't want to be paying LS320 prices for an LS80, kind of thing (the model number is normally the price in thousands of yen, for tokais anyway).