I'd certainly agree that it is possible to buy the wrong model. If you look at the Maximum Performance test report, there's no shortage of toilets which only reliably clear 150 gram samples (~ human male average waste mass - meaning a failure rate of about 50%). I'd not be so quick to say that the right model doesn't exist since I haven't tried any of the ones that reliably clear 1000 gram masses. With respect to assurances you got from people, I'd personally be surprised if salespeople at most places I might go to buy a toilet had read this or a similar report and memorized the relative effectiveness of their different toilet models.