I agree there are a great number of people who don't notice the difference... I don't think they "can't tell" though. Mention something and they'll see it.
That being said (and I know that's what you mean) I still content the majority of people already DO tell the difference!
The first time I wore my TE2 in public I got the most random people — old, young, short, tall, educated (seeming), uneducated (seeming) — all saying things like, "Why do you look better than them?" "Your armor is different... why?" and so on. People may not know what they're seeing is different, but they know something is different. One old lady said of an FX bucket, "His head's too big." She got it.
I think it's like high-def televisions. There are guys (I know one of them) who would snarf at a TV that I thought was "good enough." I know nothing about what's good and what's not... and am certainly not on TV forums and the like. But if you sat one that I thought was "good enough" next to the one that the TV geeks would drool over, I bet I could say, "That one's better and this one sucks." I may not know all the techie specs, but I'd be able to see it.
Thus it is with TK armor. People know it even when they don't know it.
Okay... off to the For Sale forum to post a used soap box.