The issue of only flushing once is not about whether the toilets leave marks behind -- it is about whether all liquid and solid waste is removed with one flush. That is what the engineers who design toilets work on.
Terry has commented on this numerous times on this site. Low-flow toilets in general perform well in terms of clearing the bowl of waste (which, after all, is what toilets are supposed to do) but "bowl wash" or the ability to prevent marks is not as good. On the other hand, we really don't want to go back to the "bad old days" when toilets would use 5-7 gallons for EACH FLUSH, but by golly you didn't see any skid marks!
Did you get the Sanigloss option on your Toto? It helps.