I found the 10 hat (with only 1 extractor trick) to be a good bo for 3v3 hunters. But it depends.
It is better than a 12 hat, that on a normal 3v3 is too slow, and it can be better than a 12 pool, because of more larva, that allows you bought to sunk more or to do more lings fast.
it is different from a 9 pool speed, witch looks for a different strategy.

in 2v2 i have found it to be much less usefull, as in manu matchupps you look for fast mutas, witch are better off 1 hat than 2 hat.