I'd guess you might be able to detect a difference in bearing smoothness. If I were in this buying situation I'd probably go with Tiagra; heck, if I were in the market for a new bike I'd likely look at what's available with a Tiagra group.
Awhile back I bought some wheels on eBay that were said to be new take-offs from a Specialized Allez with Mavic CXP 22 rims and generic Specialized branded hubs for $125. They've run perfectly fine for about 4 years now.