Hi,
I really should link to WWG but I always figure my builds are too basic to be of any real interest.
Playing time for both games is similar, given similar numbers of figures, I think. Our SoBH game took about 45 minutes, while the last WHAA game also took about 45 minutes in total. I suspect that WHAA does take slightly longer per figure to play out, but we can still play a couple of games in an evening and have time to socialise and drink beer. I think that with practice we might get a standard 300 point game of SoBH down to about 30 minutes playing time but that might be a little optimistic.
Cheers,
Ruarigh