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

The pad dimensions are the same, yes. BUT, the area swept out by the pads on the rotor is bigger.

If you figure the outside of the rotor is 11.75" and the width of the braking surface is ~1.8" ( I measured it),

then the total braking area is π (11.75/2)^2 - π(9.95/2)^2 = 30.67 square inches for the 11.75" rotors

For the 10.98 rotors (stock size) the braking area is π(10.98/2)^2 - π(9.18/2)^2 = 28.5 square inches

Yeah, sure that doesn't seem like much, but that's an 8% increase in surface area.

Next, and this is where the real advantage is, the larger rotors actually multiply the force that's applied by the caliper more than the smaller ones. This is because the "lever arm" acting on the spindle is longer.

On the stock 10.98" disks, the middle of the pad falls at ~4.59" from the spindle axis. On the 11.75" disks, it's 4.975". Once again, not a huge difference, but that's another 8% increase in braking force. The calipers apply the same force, but because of the larger diameter of the rotor the braking power increases by 8%.

Yes, it is a noticeable difference. I converted both my Challenger and my Duster from the stock 10.98" rotors to 11.75" rotors, kept the calipers the same, and you can tell the difference. The 11.75" rotors are definitely heavier, but they also provide more braking power, and better cooling (more surface area). On the street the improved surface area and cooling isn't as big a deal as on the track, but the increase in braking power is a definite advantage if you have the tires to take advantage of it. I know it probably won't translate into an 8% shorter stopping distance as it wouldn't be linear like that, but I've been in a few situations where a foot or two would have made a big difference in the length of my front fenders.