I also have multiple systems and have tried the game on an Xbox Slim 250Gb as well as Xbox Pro 60Gb.
I have installed the game to the HDD and can see little to no benefit.
I have used HDMI, and VGA. Will try the official Component cables tonight.
I have also tried every single resolution including 480p (i know thats not HD but I tried it anyway) all the way up to 1080p. No change.
The one thing that has made a slight difference is changing the Reference Levels in the display settings of the 360 dashboard. This has only affected the gamma setting which I normally have all the way to the right. I was able to see the third icon when the gamma setting was only half way up, if I set reference levels to standard and not expanded.
Everytime I load the game up I hope for a patch. Something to fix the issues. Fingers crossed SD can do the business and resolve these issues.