I glued this crack that went right through the bat and it's still holding after several net sessions. I've been told by a batmaker that the glue is stronger than wood and should hold without dowels. Seen a mates m&h repaired by the same guy with glue for a similar length crack from the shoulder downwards, he played all season without an issue - even won the division batting award using the bat.
Biggest issue is stopping the crack extending up the bat, you really have to get glue into the source of the crack to be certain of it holding.