I am interested in wilds and naturally I always wonder about them being kept in their 'natural' water. I had the oppurunity to pm wildthing (aka David Webber) from wilddiscus.com. He imports wild discus to breed and sell.
This was part of his message:
keeping wilds is easy, they are tougher than domestics IMO, as they are already proven survivors. Breeding is also the same, as you say, soft slightly acidic water, but just for keeping them that is not necessary