Anyone compare outlets?

I will be getting new lines put in and would like to know if there's a signicant difference between outlets. I see some of these things going for $50 and even $200 dollars.
I just switched my outlets to Arrow Hart 8200's, for less than $10 each, and that really helped. Can the higher cost of these 'fancy' outlets be justified or is it more hype?

Has anyone experimented with these thingies, done any sort of actual comparisons on the same system, etc.? Inquiring minds want to know.

thank you,
KP