well, the MR12 are AP only. We have remote locations with 2 to 3 devices (but 1 PC usually) and those locations need a better router. It seems silly to use a 300$ AP, but have a $50 Linksys router
Since I cannot setup an easy guest network, I think I am leaning more towards getting some Cisco E2500 with Sputnik installed. I gain a similar "cloud" configuration, although not as many bells and whistles but at least the captive portal will work