At WIA this past weekend I had more than a few people ask me why I used ash instead of the traditional beech. It was implied I was using a lesser wood for plane building. While it may not get as polished as the old dogmatic standby, ash is proven harder than beech per the janka scale. It is also almost 2x more stable, according to this chart, on tangential dimensional change coefficients. The lower the number, the less the wood moves with +/- moisture.
-- It's only wood.