I have a 3.6 and have driven a friends 5.7 a few times. The 5.7 is definitely a totally different vehicle than the 3.6 and has a great feel to it. I am satisfied with its performance although I feel there is much room for tuning. It will go 100 plus easily on the highway
that being said the 3.6 will cruise at 100 plus also.
I am happy with the 5.7 power in JGC but many on this thread feel it could/should be more powerful. You would probably feel a huge difference coming from the srt8 so you may feel different as I am coming from the 3.6.
Then there is a drone issue and a few issues inherent to the 5.7. Im sure the 5.7 guys will pipe in soon.