I do not expect common sense from a company that repeatedly confused peak detection with envelope detection in an apparent attempt to mislead customers into thinking their DSOs had the former when they actually only had the later. I ran across this years ago when I was evaluating DSOs (before the Rigol Z series was even announced) and it led me to disqualify Rigol. Ever since then, I have been suspicious of their motives. Of course this may have been common sense for them from a marketing point of view.
Your problems with them from the past are meaningless to this discussion, IMO - virtually every single company has made mistakes with some product at some point or another. The point is rather that you started this theory of yours in response to a MISTAKE that was posted in this thread by an owner (Fungus) about the way the DSO dealt with with sin(x)/x.
It does NOT make sense for it to be disabled (or enabled) to avoid aliasing because sin(x)/x reconstruction neither causes nor increase aliasing. It merely makes it more apparent.
As has been mentioned before: for sin(x)/x interpolation to be accurate, you have to have an analog input signal that has no frequency content above the Nyquist frequency - which, when 3 or 4 channels are on, is 125MHz. The normal frequency response of the DS1000Z does not roll-off fast enough to minimize aliasing for sin(x)/x interpolation - i.e. LINEAR interpolation should be used - or- to put it another way, there exists a good reason for being able to manually keep sin(x)/x turned OFF when 3 or 4 channels are on, if you need to. On the other hand, if you enable the 20MHz bandwidth limiter for each channel that's turned on, you can use sin(x)/x interpolation without problems, regardless of the number of channels on.
I would love to link to a set of screen shots or videos showing if the aliasing problem exists or not in a Rigol DSO but I do not have one to test. I can show it on other (old) DSOs and in Agilent's application notes but that is not very helpful except to show that the problem exists in a general sense. Agilent pointed the problem out to distinguish themselves from Tektronix.
Again, where are these application notes? I want to see a document describing
turning off sin(x)/x interpolation because of interleaving problems at the fastest real-time sampling rates. I can link to reams of literature about the problem of aliases in sin(x)/x interpolation, if you like.
No company in their right mind is going to include as a reason for turning off sin(x)/x interpolation that it is to conceal aliasing made worse by interleaving done to increase the real-time sample rate.
Do you mean that no company will have published literature about this made-up theory of yours?