your posts feel more like a rant vs looking for help.
the details are what's needed and you commented intentionally leaving them out, we'd all like to help, but we need information to do so.
the 2 platforms can be synced together. guessing and trying things will never work. your talking about thousands of possible combinations. Attempting to flood out a competitor will end up causing you to be the person out in the long run. EPMP2000 attempting to drown out a 450M isn't going to go well not to mention you'd be breaking the law.
back to your problem.
on your competitor, he shared his sync info with you, did you do as Eric suggested and use the sync tool? unfortunately for you, most of the tweaking needs to be done on the 450, the epmp 2000 doesn't have a lot of sync options. you can mix cmm5 timing and puck timing. you don't need to share resources.
next, the epmp2000 and the 450 both have filtered in and outputs. so likely the "noise" your getting is actually on channel rather than co-band. I'd dare say as well if you're getting noise, it's showing your uplink modulations being completely tanked vs your downlink modulations looking good. that can be seriously improved by adding the beam steering antenna. horns may or may not fix it. a lot of variables there. throwing different types of antennas at a problem doesn't necessarily clean out your noise. it depends on where it's coming from and what the needs are to fix it. if the source of noise is 10 degrees away from your sub, and same power level as your customer, it will not help. a BSA will give you some improvement. vs if the noise is 50 degrees away, a horn will do a better job. but you need to truly identify the noise before you can determine that.
if you truly are running 20 channels (100mhz apart) they are not the cause of your headache, and the timing is nearly not relevant. I've got EPMP2000 APs sitting with an AF5 that runs nearly full bore every night just 2' away facing the same direction only 40mhz off, not a bother in the slightest. 10 feet of the side of the 450 will put you well outside of the full power center of that radio.
as mentioned above, the noise will increase during peak time because of usage increases. this is something we all face, and we all have to mitigate. you can test this theory on the bench if you'd like. setup an AP and SM at the weakest possible signal you'd have in the field realistically. get them locked at say -65. with a 20mhz channel. let them the link and watch. now set a router between them on the same channel and width connect a device, but don't have it pass any traffic. you will notice some modulation bouncing, nothing bad. now download a file, you'll see it tank and possibly de-register.
next possibility is your simply saturating your frame times. during peak, what is your frame utilization look like? (monitor > performance, the bottom of the page) if you're sitting at 90% or better, you need to add capacity, it's just full.
if you can post screenshots of your wireless tab showing your RSSIs and your MCS states, we can help you resolve this problem. if you've got an inactive AP you can post a spectrum scan from the same direction, that would be of extreme benefit. or if you'd be willing to take an AP offline and the SA scan during the problem period, that would also be helpful in solving this issue.
another possibility altogether is your backhaul being bothered. what are you using to feed this site? is it a regular af5x? they don't do well with extreme noise right on them. Is it in a different band altogether? or a different radio? have you validated that it is not slowing down or being overwhelmed at peak?
what are your switches saying connected to these radios? are you getting crazy pause frame counting? so many peices to a puzzle like this. making an assumption and sticking to it can stop you from finding the source of the actual problem.
