Some other potential advantages for the C4s for open taping would be:
Balanced outputs mean you can use very long cable runs when needed.
Because they offer cardioid capsules, you can get a good stereo image out of near conincident configurations whereas with omnis you'd probably want a wide split or a Jecklin disc. So even though the C4s are bigger, they are potentially easier and less obtrusive to mount up high on a stand.