Here we go again. This time with charts, too!
I think we need to state the obvious here: No amount of data is going to ever convince me (and arguably nobody) how I / they like my / their music to play. If you want to change the HK setup b/c you don't like it? Sure, knock yourself out. However, don't complain and moan later that your FCA van is a POS b/c has all kinds of electrical issues, when you actually shorted stuff while doing the hackjob to replace speakers b/c you knew better... etc etc. I've seen people curse their cars, but when you really get to the bottom of the issue they did something, they thought it was going to fix A or B, or improve this... etc... in short, they effed the thing, b/c they thought they knew better.
The HK system in the PAC is what it is. Personally, I would concentrate in making the van even quieter rather than adding super-duper fancy painted paper cones, errr speakers... changing frequency response in the speakers, which you probably don't know to begin with, is just a guessing and expensive game, again, if you like playing money pit games, go for it... its fun, until it isn't, then curse FCA for making such a POS van.
If you include all audio systems of all cars I'd say its more like a 6.5/10, which kinda goes along which has already been stated "this is not the best car audio system to ever exist, etc".
The OP statement clearly indicated it was a waste of money, for him, in his opinion, but in my opinion, it wasn't for me. I did listened to all three and I wanted the HK.. and since you like graphs, well, let me tell you, I didn't need to bring my spectrum analyzer to make this decision. Which brings me to the answer to this matter: Try all three systems at the dealer, by yourself, use a high quality encoded music that you like listening and decide for yourself. No amount of data, personal opinions, angry posts with caps, etc, are going to prove which one is better to the listener. Beauty is in the eye of the beholder.
This kind of threads are just like feeding the trolls, and I guess I am doing just that... need to stop now.
G.