I'd say that's not the case with Icon Experience. I've not used Icon Shock,
but checked into their site after reading this thread. I'd rather have a
large library of icons that all match than many libraries of icons that are
different styles, and each library may or may not have that icon you
currently need. All of Icon Experience has the same look, and you get 2000+
images (not including hot states or shadowed-vs-non) in 16x16, 32, 48, and
128x128. Also, from browsing the Icon Shock site, the 16x16 icons look very
hard to make out to me. However, you do not get the source files with Icon
Experience, you only get png files and ico's.
I think Icon Shock would make much more sense for use in web design, where
you may want to make use of different styles of icons.
On a related note, Icon Shock's stock company logos looked very good. Their
deal of 500 logos for $99 sounds like an amazing deal: