Leave the local on 5742, and then move the peer to 5792. See how that works out and then change to adaptive or a 3/1 ratio in the direction you need the most BW. I also would bet money that if you use DSO it would have automatically picked 5792... of course that doesn't give you the flexibiity that fixed mode gives allowing use of two different channels. I'd also try using a 20MHz channel width. I've had instances where using a smaller channel width actually delivers more BW in a noisy environment.
As far as antennas are concerned, we've used the RadioWaves 2' dish that Cambium recommends, and we modified it for a dual-slant polarity in order to fight some interference a little better. The antennas are very expensive and I don't know if I actually saw really any additional performance over any other well built 2' dish. If I had to do it all over again, I'd really like to try out RF Elements UltraHorn antennas now that they have an N connectorized version. We're going to be testing a PMP450i connectorized SM that's using a cheap 2' dish right now, and swap it out for one of these UltraHorns and we'll have a pretty good idea of how they compare soon.