Has anyone had experience with kids wearing these for ISI basic skills? Are there any other options for kids whose feet are still growing?
I wouldn't recommend them for anyone - they're really not meant for figure skaters, they're basically marketed as recreational (pond) skates, and for that, which amounts to occasional use over one season, they're still not that great, but probably adequate.
I would suggest the 121's, they're good quality beginner skates, and if they are still in good condition when she outgrows them, they will tend to have a fairly high resale value because they're a better quality skate than something like a soft skate - which means that in the long run, they probably cost less than buying a cheap pair of skates which won't hold up for more than a few weeks of regular skating.
Plus, as FigureSpins mentioned, leather boots can be stretched as they are outgrown, which can buy some much needed time before they have to be replaced. Usually the rule of thumb for kids with growing feet is to get them fit, and buy a boot 1/2 size larger (but no bigger) to allow for growing room.
Definitely ask about used skates as well from your pro shop or possibly even your rink's skating director.