I appear to be unable to set the rate on newly created one shot particle emitters.
After changing the rate the particle object properly reports what the new rate should be, but despite that the original value is still used.
When I switch from one shot to continuous the rate is adjusted appropriately on newly created objects, which makes it likely the problem isn't on my end.
I'm running windows 7 x64, and have tested in both Chrome and IE.
Example CAPX here: