We can always approach this from a more general point of view. The playback which occasionally causes "white noise" played back by various programs on a whole lot of other PA equipment AFAIK has no reported "white noise" issues. If you know of any let us in on the secret (provide the link). So it only and rarely happens on Mackie equipment. iPads or iPhones aren't the issue because by now someone would have had a problem with other gear and posted it. I found the problem, it's MACKIE end of story.
I think you're jumping the gun with the blame game here WK.
I'm not happy to let you be judge, jury and executioner of Mackie, just on your presumptions.
You're becoming very "JL like" in what is sounding increasingly like anti Mackie rhetoric.
IMHO there are simply too many variables for you to state "it's MACKIE end of story."
Because there are so many variables
I won't say that Mackie definitely aren't to blame either.
Just because the white noise does or doesn't manifest itself in other equipment, does not necessarily mean that Mackie are at fault here.
Bear in mind people, before apportioning blame:
1. AFAIK Mackie released a product that had no white noise issue with the iOS available at the time.
2. iOS8.1 seems to have solved the "issue".
3. Different audio interface manufacturers have different design & construction (obviously).
An issue deep in an iOS version may or may not have a bearing on a particular piece of hardware.
If a problem does occur, it doesn't necessarily mean that the hardware is at fault (especially when considering point 1 above)
You cannot say definitively that Mackie are at fault any more than I can say they are not at fault.
WK, you are well respected here by many because of your accrued technical knowledge.
As they say, "with power and influence comes responsibility"
Until you have hard data to back up your claims, perhaps you should qualify your statements with "in my opinion"?