I think there are a lot of "it depends" on this topic. For me ('12 RT), I'm going with shortys (Flowmaster) that I bought last fall. More-or-less and in my opinion based on some research, the shorty don't add much; however, compared to the stock log style it should be an improvement nonetheless. How I look at this, it's part of the overall scheme which includes a 6.4 intake manifold, hi-flow cats, and larger cat back exhaust where I hope to net-net some notable gains albeit not monster gains.
My car is not going to be a track car or looking to street race anyone other than a pissed-off guy driving a mini van who is tailgating me because he's late getting a pedicure, but rather my goal is to have a slightly-mod-pro-tourer car with a few extra ponies. I already purchased a 6.4 intake manifold and JBA hi-flow cats to be installed and last year I installed a Hooker Blackhawk 3" cat-back exhaust. Between all these mods, in the aggregate, the car should breathe and exhaust better, and with some tuning, I should get some favorable results.
As for long tubes, in some States, this can be problematic when it comes to emissions, not to mention going catless. I would research your State's requirements before I would make a commitment one way or another. Some states are better than others. As I stated earlier, I have hi-flow cats to be installed so I'm hoping that this won't affect my emissions testing when the time comes.