Well, it's certainly a labor of love and some thought was put into it. And if it held up so far ... Mind you, he's really using thin strings ... his E is an 85. While 90ies as E strings are not uncommon with 8 string sets, the Explorer is a medium scale so an 85 E string should be a flabby affair.
I might be tempted to go after this if the eighties Explorers weren't such naff basses ... they really did the Explorer shape which I like a huge disfavor with that series. Look at an Alembic Spider to see how a Gibson Explorer bass should have/could have looked.
I also have doubts whether those midrangy Grabber pups Gibson insisted on mounting on the Explorers (they brought out a bass in the mideighties with pups from the early seventies when the whole bass world was into ultra piano rrring sounds on recordings, the mind boggles
) have enough presence to capture the octave strings in full, especially on a medium scale were the harmonics are kind of odd. An 8 string that doesn't capture the octave strings with some transparency really only sounds like a muddy 4 string at the best of times.
The thin strings and medium scale should make playing this thing easier on the hands though.
I'd give it an A for originality and innovation, but only a C- for the Gibson origin raw materials.
Uwe