Ruckus' 'Interference Rejection' is part of their 'BeamFlex' proprietary marketing, and has to do with their claims that they can use their 'smart antennas' to steer around interference. That's all well and good, but unfortunately it's mostly marketing, and if you follow their marketiecture claims, if you have clients near any of this 'interference' they will essentially be blind to the AP since it's purposefully ignoring any RF from that direction.
Every vendor deals with interference, and yet somehow not everyone needs this proprietary interference avoidance mechanism. And while the marketecture sounds goods, there is a gross lack of detailed information on just what types of interference it can avoid, how it avoids it, and what the consequences are for clients sitting in the area of the interference.
Aruba's APs have up to 18dBm per chain of RF output, or 21 with MRC. We have mechanisms to deal with interference that are most standards-based and don't end up rejecting clients or putting clients in the AP's blind spot' (as Ruckus claims it would do by steering their arrays away from 'interference' which they never fully describe or articulate). We also support the adjustment of what we call 'interference immunity' which essentially can de-sensitize a radio in high interference environments.
So if your hard requirements are based on proprietary Ruckus technology, then you're stuck with that. Otherwise, the 103 or 105 would work fine.