If all they do are drills, then adding additional players is going to be a negative for those already in the program.
That said, the 7th-8th grade group seemed fine to me. Lots of touches, plenty of running. Room for more? I think so. Is that ideal? Maybe not, but 4 or 5 more would not have much of an impact.
And if they start scrimmages, another line would probably be welcome. The boys have to cover a lot of room with just 5 players on a side, and having to play offense and defense will be exhausting (good!). Adding a few more boys in that context can only make it better, and might even be necessary. I believe the target roster in box is 12 players ... 24 total for scrimmages. Not sure if they have maxed out at 24 in the 7th-8th grade sessions.
In any event, my son loves it, and if they form teams or have some sort of winter league, he's in! The best way for that to happen is for more kids to give it a try. | 
