my girls little cousin is 12 and he actually really enjoys his .410 shotgun... he hates shooting our 12gs... remington 870, mossberg 500, and an old remington 1100....all 3 were too much for him...theyre heavy and long, not really a kids gun...all kids are different though...if you dont think your kid is big enough to handle the recoil of a pump, then the semi-auto is not a good choice....while it may kick a little less, its not substantial...
maybe look into a 20g pump....you can get one for about 1/3 the price of the remington 1100 and then in 4 or 5 years when the kid is more comfortable shooting and a little bigger, you can then step up to a 12g semi auto......and you will know by then your kids shooting habits, you will know if they really enjoy it and do it often, or if its a rare occasion kinda deal...itll help you decide how much to spend on the next gun since its not one they will outgrow, and one they will keep forever
the only thing about getting a youth model or 20g semi-auto of any kind, is going to be how soon will your kid outgrow it and want/need something bigger? would hate to spend too much on a gun that is going to be resold in a few years....be better off buying a cheap 410 or 20g pump and letting them beat it up until they can handle a full-size 1100......just my opinion