is it worth swapping 10.7 inch discs for the 11.8 inch?

Drilled and slotted rotors will not increase your stopping power.

They may slightly improve cooling, but a lot of people are going away from drilled rotors and just doing slotted. But, again, that still doesn't actually increase your stopping power. And on the street your brakes aren't going to get, and stay, hot enough for either of those things to be really useful.

Yes, my disks are drilled and slotted. But I couldn't tell the difference on the street vs the plain ones, I just was able to get the drilled and slotted version cheaper when I bought them for my challenger. I run the drilled/slotted 11.75's on the Challenger and had plain 11.75" rotors on the Duster. If anything the braking on the Duster was better with the plain rotors, but I assume that's because its a lighter car and had nothing to do with the plain vs drilled/slotted rotors. I did get my 13" rotors from Cass in the drilled/slotted version instead of just slotted when I upgraded the Duster, but I don't think it makes much difference.