I would love to see this testing become widely available if it proves out.
And, yes I would pay more for guaranteed IBD free snakes backed up by documentation from a licensed vet. The test would also have to be very recent (just prior to shipping, ideally as we never know what animals are coming and going from any facility).
Let's face it IBD is an issue even for reputable breeders. We may never clean up the shady characters but, for serious snake enthusiasts and reputable breeders this has the potential to help clean up our collections. Possibly even eliminating IBD as any sort of serious concern for anyone dealing with reputable people. There is nothing to say that some of us do not have snakes that have been properly quarantined and have an asymptomatic carrier still, I have not read enough on the subject to say whether or not there might be a gene that prevents actually acquiring the disease even if infected or, if stress (such as less than ideal conditions which is something I think every one of us tries to avoid) can make an animal more susceptible.

I found it interesting that there seems to be a direct rodent link in that the virus seems to be from a group known to affect rodents. That said I'd be willing to pay more for feeders from a company that regularly tests there colonies for this virus if it is ever proven as a vector.