I tend to agree that the when it comes to a tamper it's what you personally like. With practice, anyone can get equal pressure and distribution with the majority of the tampers out there as long as they correctly fit your portafilter basket. IMHO, with practice you can get the same great pour using the plastic tamper that came with your machine that you would get with that $80 Impod or Espro. I just don't like to use the plastic tamper because it feels flimsy and just doesn't look like a quality tool sitting on my counter. Of course if you're a professional barista a good tamper could reduce arm and wrist strain but for most of us "Home-Baristas" this is not a major concern.
I recently started a thread over at CG that discussed the need for one of those beautiful $$ tampers. Some individuals posted some impressive pours using just that little plastic tamper that came with their machine.
http://www.coffeegeek.com/forums/espresso/general/159908 I've also heard many people say that they threw away their plastic tamper because they expected it to break. I don't know what plastic they were using but the ones that came with my machine and grinder are not going to break under normal use. In fact, I tried as hard as I could to break one with my hands and I couldn't even bend it. I even stood on it and it didn't break!
Getting back to high quality tampers. When you get down to it, the bottom quarter inch of these tampers which actually come in contact with the coffee are essentially the same. If you took all the fancy tampers out there and cut off the bottom face of the tamper would be able to tell which is which? I don't think I could and I spend WAY too much time fiddling with espresso tampers.
For me it boils down to what I like. I want a tamper that has some weight to it and looks good on my counter. I have to admit that my tamper choices are also functional status symbols just like my Illy alien and bodum cups.