So those of us who love our cats view the litter tray as a necessary evil and a helpful early warning system.
We have some who will do crossed paws but will eventually use a tray and others who don't care but have a preference for one of the 3 types of littetr we use - wood pellets, paper and clumping which our latest 3 ferals used when in pens waiting to come to us of course it is now the most popular!
I don't particularly mind them using the trays, I just think its more hygienic that they went outside but I would keep one inside in case of emergencies like everyone has said. Oh well, I will just hope that they do the majority outside when they start to get older and keep my eye on what they do, do, inside.