I like the idea of saving money for me and my customers, but also like the idea about not worrying about the next phone call being a disgruntled client. I promote the outstanding lightfastness of Vivera ink as one of the things that distinguish my printing business, and sleep easy knowing that I'm using an ink that tests better than any of the rest. None of us knows if 200+ years is really going to be anywhere near that long for lightfastness, but I think we can agree that is will last longer than ink that tests at 70 or 100 years.
I know firsthand of a printer that switched to third party bulk ink for his Epson printer. He didn't say anything to his clients about it, but just a year later he began to field complaints from customers who were noticing fading of his canvas prints. A quick Google search turned up his bragging online about how much he had saved when he switched to bulk inks. His clients quickly became his former clients.
This printer's case might be an extreme one, and it might not, but we can only guess since Aardenberg Imaging or Wilhelm Research are unlikely to have tested the ink you might be using.
I'd consider running a third party ink if I had an extra printer that was dedicated to display printing, but if you are printing fine art prints that are expected to be long lasting and "archival", make sure that you remain anonymous online, as this post may outlast your prints.