I don't think you can ignore the benefits of pulling in more photons per unit time and the likelihood that you will end up with more resolution. There's more than one thread here about big scope versus small through poor seeing and what the final result will be.
I suspect in this case the question is more about CCD real estate size than scope size. It really is genuinely hard to evenly illuminate the larger CCDs becominga available to amateurs, but its hard to ignore how nice it is to swim around in the big fields they can realise rather than having to resort to mosaics.
Personally I'm constantly amazing and pleased by what my relatively straightforward 8" rig can do, so thank goodness we don't all need 16803 chips and 8" Taks (even if they did make them...
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