Hello,
Regarding - "I understand that Aruba access points can be used for this controller?"
That is not my understanding.
I guess you could use the RADIUS server on the MSM as an external AUTH source for an IAP cluster or something "loose" like that.
If you want integrated Acees Points with an MSM Controller, MSM series Access points are your best bet (MSM460 for G/N and 560 for 11ac).
I would look into whether it would be worth going "controllerless" with some Aruba instant access points or IAP's as they are known. I find the IAP series are a doddle to manage in comparison with the VSC based setup on the MSM and the IAP has loads of added value with the Web filtering, Facebook Guest login, auto clustering for high availability under a "virtual controller" and VPN backhaul capability.
Kudos and Solved buttons tell others that posts are useful / helpful - don't be shy - get clicking
Thanks
Ian