Re: Supercharged 5.7
If you search through threads here, you'll find one or two 2011-2013 WK2s that have supercharged their 5.7s (thats how many I found, but I am not perfect, there may be more). They seemed to agree with your 300C opinion, they liked it. I am not sure if any 2014+ guys have done it yet, but it doesn't matter much, as the 5.7 didn't change much.
2014 Jeep Grand Cherokee Limited 4x4
5.7L Hemi V8, Luxury II Package, Navigation
Hemifever Tuned, Billet Catch Can, 265/60R18 Hankook Dynapro ATMs