Several combinations available to you and probably lots of different answers.
Here’s our thoughts, back when we only had 2 boxes.
In your situation I’d use one on 250DR for sure and the other could be tried on both NDX2 and HiCap to see which you prefer.
If you search the forum, people report positive effects using one on napSC but never having owned one can’t comment on that. Probably the last place to try.
They’re a worthwhile investment, we now have 5.