If his strike rate is as high as he says it is and he proofs his bets to an independent source (so everything is verified), then yes it`s absolutely worth it (depends also on what he will charge you against what you are prepared to stake so to ensure that value remains).
Betting successfully is often about value and exploiting generous bookmaker pricing on a horse/a sporting event etc.
We have much success also and only posted a thread about it yesterday -
https://gfy.com/showthread.php?t=1150207