Nah, without knowing me it's hard to really take how I respond in proper context, I've got no reason to lie about being pissed or not so you'll just have to take my word, not bothered, not pissed, not rustled, just sharing my point of view.
Would be a good test. Your assumption being that they should show similar gains (as a percentage of total BW or starting strength etc).
How do you measure and account for things like base metabolic rate that is shown to differ between individuals regardless of body type? http://en.wikipedia.org/wiki/Basal_metabolic_rate
Even in that article it mentions 26 or so % of the variance was unaccounted for.
And you don't think people can genuinely be self describing as "Ecto" (knowing what they really mean is just hard gainer) and not see ANY basis for that claim? That seems like a pretty sweeping generalisation dude, I'm no scientist and I'm often wrong about things but you've got to at least consider that there may be some truth in the idea that some people struggle to gain, and some others likely struggle to lose. I'm like you, I can go up and down as I please now that I know how far away from maintenance I must go to achieve it, in my head though, maintenance is different for everyone and how far you need to move away from it to achieve your goal can also vary widely.