Yew is very variable, sonetimes it works beautifully with edged tools, other times it tears and has to be worked with a rasp. (It has nothing to do with it's country of origin!).
It doesn't matter much on the belly of the bow. The thing you have to watch out for is rot in the sapwood, but this on;y applies if you have a sapwood back.
Yew heartwood backed with Bamboo, Hickory or Ash is a great combination.
Del