If you are looking at a 2015 limited and R/T, they both come with the 20" wheels, so everything that is said above about the handling because of the wheels does not apply, I think it comes down to what you need/want. There are a few key differences between the limited and R/T, but I don't think you will noticed any difference in performance of handling unless you plan on road rallye racing with it. I have the SXT rallye package and I can take hard turns while punching the gas and never lose traction to the road. But the key difference in the limited and R/T is the V-8 motor, do need the power? I prefer the v-6 due to gas mileage, I never tow so didn't need the extra power and I don't race, so didn't need it for that either. The v-6 has plenty of power for me and after adding the air intake system to mine, it added a nice subtle deeper tone to it as well.
It really comes down to if you need the power and what look you want to have.