Hey Bill,
The risk is always there, even with reputable dealers. I have purchased emeralds from folks that advertise regularly and that I see from time to time and have lost them. I would still buy from them and have. Even someone that has a keen eye for picking out good animals from shipments can't be right every time.
Every wc emerald we purchased was a great eater, however little signs like undigested bones spoke of problems to come. Eventually the puking started. Probiotics didn't help at this stage nor benebac and even with vet care we still lost them. Most lasted up to 18 months with no puking problems for 8 to 12 months. So out of 13 wc's we got 3 healthy, thriving emeralds of which 1 female gave us babies in August of last year. The ones for which we had necropsies done, showed the renal failure that you mentioned. I have decided that I won't consider a wc emerald LTC for 2 years with no problems. I have never had a problem with wc basins but know folks that have. Personally, new blood for breeding warrants the risk, but it is sad when some one buys a wc as a first emerald and looses it. This puts a bad light on the species as a whole and is probably the main reason for the myths about how "delicate" a species they are to keep and in some ways is responsible for the reputation of being nasty as sick emeralds can be quite grumpy.
If you decide to purchase one of those 4 month captives, just keep in mind what you already know about the risks involved and don't necessarily consider the seller a "bad guy" if you loose the animal.
CraigC
