If it's the new J you should have no problem. My wife and our children flew the new J, and it's just fine. If it's the old J, then yeah, it could be troubling. The only advantage for PEY is that you sit right next to your son, but the armrest do NOT fold up, so he can't lay down on you and stretch out. However, it does have a very nice recline and that may make your child feel better, and safer being right next to you. Definitely worth it to consider, but yeah, you are doing yourself a big drop off in service and meals.

If you can afford it, upgrading to first might be the better option.