A lot of the kids preferred the new/er iS50 over the previous PrKids for kids sized slalom and blasting - despite we preferred to offer a dedicated Kids slalom shape, the kids decide the iS50 was so good they prefer that. As long as there is enough wind and the kids are powered up, it's quite an OK choice (as commented above by Ola /JM)..
Then on the other question Back vs Front foot /Missile vs iS50 (which seems actually quite different question to TJ's question) iS50 will be more back foot when tuned with large (~28) more upright fins and bigger sails, when tuned for downwind speed with smaller (22-24cm) fins the iS50 is very neutral. With a board as small as iS50, even a small change in tuning can change the board trim a lot.
Cheers ~ Ian