What is the Pros and Cons of using 2.5ms & 5 ms Frame Sizes?
little more throuput
little longer latency
2.5 ms frames:
little less latency
little less throuput
Also, if you are trying to Sync with other gear (for example, with your own Motorolla Canopy PMP 100, or with some nearby competitor running 2.5ms gear) then you need to use the same frame size between all SYNC'd gear.
Ive noticed my BER go way up when I switch from 2.5 to 5ms on the 450m/I.
You should probably start a new post outlining the issues. If I had to guess, by changing to 5ms, you may now be interfering with adjacent radios that are using 2.5ms frames. In a greenfield environment, you should not see any differences in BER between 2.5 and 5ms frames.