Agree with Neil. I do use an upwards piece when someone much lighter than me is belaying, which to be honest is pretty regularly.
I actually think in some situations an all upward piece anchor or even majority upward piece anchor can be pretty unsafe. It means that if the belayer sits on the anchor, which I do all the time he could accidentally pull all the pieces, fall off the edge, pull the leader and both hang in space off one piece, laughing hysterically. |