Originally Posted by DaveSSS

I couldn't comment unless I had inspected the rims for important feartures like welded and machined joints on the braking surface and inspected the hubs to see how the freewheel mechanism functions and determined the type and quality of wheels bearings. Most rims these days have machined braking surfaces, but some don't have a fully welded seam. Mismatch at the seam can result in an annoying ticking upon braking. Even early model Campy wheels, like the Shamal and Eurus had this problem.

Of course there is also the actual weight to compare.

Flex would be a function of the spoke number and pattern, flange width and spoke tension.