I'm not an expert at IMC, but from what I've seen, I can generalize things as:
IMC:
Geared towards what's in your data center, the wired side of things. It provides in-depth visibility into ports with a capturing path from the gateway uplink to the edge switches - and knowledge of the what terminates on those edge switch ports. This is infrastructure troubleshooting.
AirWave:
View of both the WLAN and the LAN. A view from the client association path through the APs, controllers, and switches. Provides trending and reporting, as well as alerts. I consider this client side troubleshooting, meant to provide clients the best QOS. There's also a roadmap to increase LAN visibility to be comparable to IMC.
Wired:
If you're dealing with only wired side issues, IMC is the current path.
Wireless:
If you're looking for coverage of the wireless, then AirWave is the way to go.
Both:
If you're looking for wired and wireless, you might try AirWave alone. Since the wired coverage isn't complete in AirWave, you might also consider trying to run both products.