The difference between 8mm and Hi8 is just a little hole that has not been drilled out. Looking at the back of the tape. look at the left side. 8mm tapes have one hole drilled out (top right) Hi8 tapes have 2 holes drilled out (top right, bottom)

I found a whole bunch of 8mm 3M data backup tapes for computers at a swap meet. They all worked out of the box as 8mm in my cam. Now they all work perfect as Hi8

As for D8 cams, I've always heard and read that the Sony 350 had the best low light performance, and at the time the beat all the consumer DV cams too. Not sure about know as in the last year a lot of improvements have been made to consumer DV cams low light perfomance (JVC comes to mind)