I just noticed this thread and love the question posted.....
I too when I was younger and poorer, started with brands like Caressa, Allure, Spanish Leather and Pepe Jimenez....I learned quickly during that phase that the materials used made a huge difference in comfort...i.e. leather linings, leather soles much better than synthetic materials....
As my tastes got more expensive, I noticed that I tend to find the shoes made in Italy of much higher quality than those designers that have them made in spain(sorry to the Stuart Weitzman fans-SW made in spain) although SW is a pretty good label.....
But just because they are made in italy, does not mean they are more comfortable.....I think different designers have different ideas of what shape a foot is and how they design to fit that foot.....Although I am a huge Louboutin fan, very few of his style I can honestly say are really comfortable, at least not until they are well broken in.....on the other hand, Gianvito Rossi and Sergio Rossi's with a 100mm heels, I can walk and stand all day in complete comfort and look fantastic doing so.....
I do think designer shoes are more comfortable and better made, especially those that use Italian craftsmanship.....
And I do think to a point, these designers are sort of worth the extra money, but there are limits.....i.e. I mentioned I really like Gianvito Rossi pumps, which sell for $695, but I recently discovered M.Gemi, which makes a very similar pump, also made in italy, that sells for $248.....very similar looks, both equally as comfortable.
I have to admit, though, that I seldom buy designer shoes at full price, and mainly take advantage of biannual sales that they all seem to have(usually 30-40% off original price)....
Anyway, my two cents...for what it's worth....