We have a couple junior yudansha that are, I dunno, ten or eleven or something. With each other they extend
and look mighty powerful for all their littleness. With adults, or at least with me, there is almost no power there whatsoever. Honestly it feels like training with a butterfly.
So when working out with them I think, OK, I will train with a butterfly for a while and practice staying connected, ultra-soft, and muscle-free. It is fine for a while, and absolutely yields some benefits. Later I try to pair up with the biggest bruiser on the mat, just to balance things out
Ultimately I agree with Don:
I enjoy training with kids, but if I was limited to that, I'd be upset and switch dojo myself.