Keith E., if you were looking to change the gears in your '14 to a set of 3.55's I would say that you would enjoy the switch. I believe it is a fairly expensive modification so you would have to decide if the cost is worth the reward though.
My understanding is the new SP's have a 230 mm rear end (even larger than the 226 mm in my Mopar 11) and is only offered in a 3.09 gear ratio. I haven't seen anyone offering different ratios in the aftermarket either.
I haven't put a bunch of miles on my SP yet, but so far I am loving everything about the car. I was very impressed at how well my M11 ran and drove but it took about 1 block in the SP to realize this car will run circles around the M11. I'd recommend you drive the 392c.i. with the 8 speed before thinking about changing the gears. First gear in the SP feels a lot like 1st gear in the M11 with the 3.92 gears.
A final note: The M11 ran close to 3,000 rpm's at 70 mph. After driving the SP (that turns way less RPM's) I would say the SP will be more fun and comfortable to drive on extended trips. Always felt like I needed another gear in the M11 out on the highway.
Hope that helps.