We started using Xirrus at our College about 4 years ago. After a little tuning it turned out to be amazing and has never let us down. It's also still going strong. Since then we started helping other schools and now manage 1400 radios across multiple sites. I'd highly recommend it. We have tried the Ubiquiti offerings (UAP-Pro) and although it was very good for the money, it did struggle to perform when put under pressure. We've also looked at Aruba and although I'd go so far to say it performed the same as the like for like Xirrus offering in an education environment, the support costs are high.
We are now a Xirrus partner so if you need any further advice or some test kit, let me know.
