There are some telltale signs, often readily visible upon inspection, that will give you an idea of whether a toilet will work well.
First, look at it from the side and study the trapway. You want one that makes smooth curves and no sharp angles. THen, look at the insides and see if it uses some weird flushing mechanism (Kohler is famous for this on some of their stuff) - you want stuff that is readily available and not cost an arm and a leg to repair when the time comes (and they all need it eventually). The last thing is how well was it actually built...Toto has very good quality control and probably the lowest defect rate in the industry. A great toilet that has a defect is no longer a great toilet! That rarely happens with Toto. So, to overcome some of that, you need to inspect the things carefully. Check the floor for level, set the toilet down on the floor, and see if it rocks, and if the top is level. ARe there any chips, sags, or other defects visible.
But, the end test is how it works for you in your home. The MAP tests don't do a great job of testing for things like bowl wash or the kids emptying a roll of TP into the thing, or someone that creates logs. The MAP tests uses plastic wrapped paste, so it is very smooth, and not a true representation of the real thing. It is repeatable, though. The guy who designed that test says anything over 500g should be fine. SOme manufacturers design for big numbers that don't actually work that well in the real world.
