We mostly care for the RCA rate up to a certain limit; say (3.51%, $25K) for NACCU. With Kasasa offer, one nice bonus is for the rate higher than the set RCA limit. NACCU offers 1.01% for fund higher than $25K. So one can get the rate of 3.51% for fund up to $25K and 1.01% for fund larger than $25K (e.g., for $50K, $25K is earning 3.51% APY and the remaining $25K earning 1.01%). This bonus comes handy for people like Scott, who are concerned about millions of dollars for deposit (nice problem we all would like to have).
Another example is Chemcel FCU with the (3.51%, $20K) and (1.01%, over $20K) tier. http://www.chemcel.org/rewards1.htm