I was out an about when I ran out of gas, and had to go all 87 octane straight gas.
Since then I've driven about 200 miles with no noticeable performance difference. I'm not noticing less power or pinging.
Acura recommends 91 octane fuel for this vehicle, but being a modern vehicle with electronic ignition and a knock sensor, it can run fine on 87 octane. You don't notice the power drop under normal driving.