I have a question for you vintage toilet experts. I happened upon a vintage toilet still in use a while back with the forward-facing trapway. It had a siphon jet and large rim jets at the back of the bowl, rather than the front, and a small waterspot much like today's low-flow designs. I was struck by how logical this design seemed from a flow standpoint. It's a much shorter distance from the tank to the jets lined up with the opening of the trapway than on today's nearly universal reverse-trap designs. Could someone tell me what advantages the reverse-trap has that caused the forward-facing version to be abandoned years ago?