Agreed to a degree.  The leading edges of the hi/low digital squarewave signal can be severely rounded off with audio bandwidth (mic) cables.  I've seen visual examples on a scope - it is clearly visible - I was slightly shocked!  Afterall, a square wave is basically of infinite bandwidth, so once you "filter" this squarewave by running it through limited bandwidth audio cable, the output is no longer "square" at all.  Not nearly enough of an issue to cause issues with getting a solid "lock" in most cases (read about one exception on this very forum a few weeks ago), but enough to increase jitter by a measurable degree.

Assuming the Genelecs can cope with Jitter fairly well (as most good DAC's can), I doubt you'd hear much difference TBH.  If I was clocking an AD converter over AES (which I probably wouldn't do anyways ), I'd be sure to use AES cables to insure the AD recieved the cleanest reference clock possible...

I'd be curious if leaving the Mic cables in place and adding a BNC Wordclock sync reference (with proper BNC cabling) would have the same effect as swapping from Mic Cable to AES cable?  An experiment for another day :-)