Oh you are a brave man, cactus tone. You knew you had it coming, yet it still came! Fwiw I think that this is a perfectly valid question in the philosophical realm, because there are production differences and even if digital bits seem like they make perfect copies, a change in say the clock will make the bits move at different speeds (don't ever let anyone convince you that digital is different to analog- its the same physics just with different information encoding and signal specifications). There's also a great question on subjectivity: if you think that there's a difference and I don't, who is correct?
However in practical terms you probably don't need to worry, if only because so few of us (are lucky enough) own one, and maybe some folks might own an older model too, or maybe some real serious artists keep a backup because their life depends on it. But nobody except FAS are really in that privileged position of auditioning that many. And really, there are so many parameters that change the sound intentionally that it would be hard to correct for those differences. The most you could really worry about is clock jitter, but I'm sure that spec is peanuts.
Most digital system failures I've seen are related to bad circuit design, where say the production variance of one output (say a reset line) means that the input of the next stage doesn't consistently interpret it as high or low. This will emerge as update failures for example. You should look at the statistics of the tech support forums really to get a sense of whether this kind of system unreliability is a feature of FAS products. It doesn't seem terribly high.