Well they do still have some kick so don't set the little fella on one TOO soon. They only weigh around 7.5 pounds so they are fairly light and still have a bit of a kick. Granted they aren't as hard kicking as the 12 gauge but they will still wake a fella up. If the little one will be growing up and learning in a non CF area where ML'ers or SG's are the only options, I personally would suggest getting a nice inline. You can tailor a reduced load like a 220gr pill over say 70gr BH 209 and still have a very good whitetail dropper out to 75 maybe even 100 with a good reduction in recoil. You can also build him up using a ML'er. Gradually increasing the charge and bullet weight's. That's the beauty of a ML'er. Working a new shooter up rather than them having to deal with a hard punch right off the get go.
As far as for yourself, as I said earlier, you wouldn't be going wrong at all with the 220. Great accuracy from just about every slug brand I've seen them fed. It seems most I've seen likes those Federal power shock 3/4 ounce the best but some like the new superformance hornady slugs with those monoflex bullets. I think the bullets in those are 250 grain. The trigger in those are pretty nice as well. Most SG triggers aren't the best feeling because shotguns are typically used differently and a different "pull" is used. Savage uses their accutrigger in the 220 and those triggers are pretty good. I'm a "trigger snob" of sorts so to get my "okay" on a trigger says a little something. A good trigger is always needed for accurate shooting.