Thanks for posting that Phil. I'm not overly concerned with the size. The only detriment that would generally cause is that it might sting corals or get sucked into a powerhead. In the system I'm designing, corals are an expendable afterthought and there is no chance of it getting sucked into an anemone.
.... The reason I didn't consider H. mag as a candidate for A. thiellei is because it does not host A. sandaracinos in nature. I believe A. sand to be one of the parents. S. mertensii host both of the clown species that I believe are the parents of A. thiellei.........
A. thiellei - (Philippine Island) S. mertensii
A. ocellaris - (Darwin) S. gigantea
A. leucokranos - (Solomon Island) E. quadricolor
A. barberri - (Fiji) E. quadricolor
A. latezonatus - (Lord Howe Island) H. crispa
A. nigripes (Maldives) H. Magnifica.
My leucs had a mag in their display for over a year but showed no interest. They preferred the quads for some reason.Magnifica check this out. here is mine in their short stint with their mertens
My concern size wise is that in a 24" cube the Merten's will soon be touching all four sides of the tank making circulation and viewing difficult, not to mention it will take up a large portion of the volume of the tank and not leave much space for water.
I was thinking perideraion x ocellaris in a magnifica, forgetting that ocellaris live in merten's as well.
On your biotypes, if it were me, I would switch the leuc's E. quad for the latz's H. crispa. I have never seen a pic of a leuc in a BTA, always merten's or crispa, whereas I usually see latz in BTA's, sometimes crispa. They are your tanks though.
Since you have the connections to get pairs of thiellei, leucs and latz maybe you have the connections to get a merten's as well.
Good luck on your project. You will need to post pics of the tanks as you set them up.