When you make this fix, can you make it possible for the cart to compute and give the member pricing (when a member is logged in) but not show the member pricing to regular customers? I don't even care if the logged in members see the price or not, as long as they (wholesale customers) get the discount assigned to them.
I've had problems with member pricing in the past (see post from late May - mid June), still unresolved. Even uninstalling and re-installing the cart didn't fix the computation of the member pricing in the final checkout step. I wonder if it has something to do with me not wanting to show the prices...