So me and the wife are adding a third bathroom to the house, it's going to be small and used primarily as a pool bathroom, so we don't really need to pimp it out as far as fancy fixtures. The City of Austin offers a $75 rebate for toilets with a 1.6 gallons-per-flush capacity, but a $200 rebate for ones with a 1.3 gpf. It looks to me that I could get a cheap toilet almost for free if I go with the 1.3, but that seems too good to be true; am I missing something here, is there a big disadvantage to the 1.3?