One thing I notice from my resent experience on wireless gaming is that N mode on 5Ghz seems to work well of your in close proximity to the router. I was on XBL using a N adapter for Xbox and it worked better then the G mode on 2.4GHz. Of course I was not on a 4500 router. I was using a DIR-628 router and using a bridged NG WNDR-3700 as an AP connected via LAN to the DIR-628. I tried the G mode only on the 3700 and it could not keep up for some reason even though it had more signal strength. I switched to N mode at 5GHz and had much better gaming experience. I'm wondering if your PS3 could be better served if you could get a N, 5GHz adaptor. If your in the same room as the router, maybe 5Ghz would work better for you for Wireless gaming. My 2 cents.
BTW, I'm home now, glad to be back on the 4500 router system. hehe.