Luckily there isn't a huge amount of functional changes from the models that Airwave supports to the 321. That said, we tested Airwave out on our current Juniper wifi infrastructure, and it's definitely got some glitches. Controller clusters in particular seemed to confuse the hecke out of Airwave.
With the recent partnership announced between Juniper and Aruba, however, they have at least commited to cross platform monitoring, so in the nearish future you should be able to use Airwave for your day to day troubleshooting and monitoring. For now, though, I'd plan on sticking with either managing the Juniper directly or via Ringmaster.