Trev might be better to ask..... I TRY to breed rays. Trev BREEDS rays.
But in regards to what you're asking...... I've lost several females over the years and I'd guess stress induced by males to be primary cause. Once they get tore up I start watching closely, first time they miss a meal the male gets moved. Females WILL damage the claspers if the males don't get the hint, but usually the female is the one that ends up worse off, quits eating then it's a fight to bring her back. Problem is most don't understand the importance of separation till it's too late, then by the time another tank is up and going the move to that tank is the nail in the coffin.
I've got rays that are proven breeders, arrived pregnant and have never produced pups for me. IF you ask me, rays aren't going to be near as likely to breed in tanks like we have - predatory communities. IF pups are what you're after I'd be tossing them in a 180 by themselves and baby them - lots and lots of food and very regular water changes.
My theory is that this is why I have so much trouble getting any pups. Too many rays, of too many different species in with too many other fish.
My thoughts are to keep the lady rays happy in separate tanks on the main system, use the largest tank for the display/ predatory community tank and just keep males in there, then move them in with the ladies, then back out after they get the deed done or hurt her, whichever comes first.