The guy who designed the MaP tests says anything over 500 is great. Some manufacturers have figured out how to make them look great on the MaP test, but that doesn't mean they actually work well with the 'real' stuff.
Depending on how old the current toilets are, they may use anywhere from 3.5 to maybe as much as 7-8 gallons per flush. Those WILL have better bowl wash...there's only so much you can do with 1.6 or 1.28g - but, add in SanaGloss and good design, Totos work quite well. Streaking is mostly a function of diet...some get them, some don't.