Yes, that would definitely help. However, you are casting quite well with the 7, and I would put the money toward a stiffer rod if I were you. They can often be found on ebay for quite cheap.
The tan line that was on the 10' loomis rod you tried was underlined by at least one line wt and you were doing well with it also.
The other day was a bad day to really try things out with the wind blowing and gusting in at speed from behind and onto the casting arm side for the most part.
On a calm day you can slow down your casting tempo a lot, and really start working on minimum force to get the line to barely turn over - working on a slow start and accelerating to a stop.
You do not "creep" at all that I could see on your forward stroke. That is what I had expected from what you described a long while back, and that is really good. I believe your biggest problem is the rod. You have outgrown it.
We'll get together another time on a very calm day in a field someplace, like that baseball field, where there is no distracting water around with fish in it.
Then we can both concentrate on casting.
Those pics were great. I hardly ever have a camera with me.
Edit: I just re-read your post and see you have a 6 wt line already. By all means give it a try, I think you will find it will work better on that rod.