Vampire and Dragon's Fury both have throughputs that are over 500pph, they're in the region of 600pph. Ideally they'd have throughputs of over 1000pph.
If Jumanji has 'solved the capacity problem' for shuttle coasters, then I'm sure we can expect a throughput of at least 700 or so people per hour. Not expecting 1000pph for a shuttle coaster as that's just impossible for a coaster of this length.
To be fair on Jumanji though, two thrilling family flat rides (if the ones on Chessington Buzz's Project Amazon minisite are to be believed) are being added to the area as well, those should help to absorb the crowds.