We use HPE IMC 7.3 as our NMS for HP ProCurve (still running HP ProVision operating system) and newer Aruba (with latest ArubaOS-Switch operating system which is the rebranded/enhanced old HP ProVision os), no problems so far.
IMHO HPE IMC is more suited to DC usage while Aruba Airwave focus really well on Wireless and, secondarily, on Wired devices (as HP/Aruba Switches)...if you have Comware 5/7 or newer Aruba 8400/8320 it lacks some configuration features but it should still have some monitoring features (for Aruba 8320/8400 HPE IMC 7.3 lacks too). From this point of view HPE IMC is ahead (can manage Cisco's devices and more other vendors' devices).
Probably if you are dealing with an Aruba-only set of devices and you plan also to have Aruba Instant (controller-less) or Aruba Controllers - or a mix of them - as core of your Wireless infrastructure...Aruba Airwave 8 (Airwave 10 is on roadmap) would fit better since is mainly - let me say that - sort of Aruba for Aruba.
For sure HPE IMC can be tested 60 days free.
Don't know if Aruba Airwave 8 offers a similar approach (probably yes but I'm not sure).
Edit: this thread on Aruba Airheads Community (Network Management section) could be an interesting read.