We service and area with a lot of ubnt, and looking a moving to the 450 and/or epmp 2000. Some aps show more than 40 other ubnt aps and a few home routers. How good is the 450(i) at working in such an enviroment? look for real world examples.
I didn't capture a screen shot but basically I have an unknown device that someone dumped right in the spectrum I was using and I wasn't even aware it was happening. That electrial filter did well for me and I trully belive if I would've had another device with out that filter I would've known about that device due to problems vs just doing a random spectrum scan.
However, keep it mind it's not a mirical device and interference happens on the reciever which my SMs are not seeing. I also am not deploying 450i SM and am using the 450d which do not have the filter inline.
Ubnt jams like crazy in my experience. The 450s can get through it, but you have to be very picky about your frequency selection and may have to use 5 MHz channel widths to get into the gaps in noise. I wouldn't expect the ePMP to do anywhere near as well. Definitely use dishes and improved antennae wherever possible; every little bit of signal will translate to more capacity per AP.
On the upside, everything I hear about ubnt indicates they can't handle interference at all, so hopefully adding pmp450s to an area will cause whoever is using ubnt to smarten up and use a real product.