This is some really fantastic work. I've got professional experience with photoshop and I can help you round out your gui. Let me know if I may be of assistance.
I've also got a few suggestions, if it will help. I'm considering this as a homebrew channel replacement rather than a system menu replacement. I feel like it's a lost cause trying to develop loaders for installed channels when the system menu does a fine job. I don't say this to insult you, but rather to suggest that it might be a neat idea to make the disc and installed channel buttons an on/off toggle option in the menu. Another related point is that I found the earlier layout to be original and aesthetically pleasing. My coding skills are poor, so I don't know how difficult this might be, but providing an option for switching layouts would be a nice feature. For example, you could have a "system menu" layout, a cascading layout going from top left to bottom right, a layout like your original version, and a list layout like the homebrew channel. Then, to select the preferred layout, you could just provide an option box in the congif menu.
Also, and you may already be on this page, I thought it would be neat to have an app specific fullscreen image come up when you click the menu items, one that would be different from the standard icon. For instance, if the icon is icon.png, the fullscreen image could be something akin to bg.png, and you could even provide the option for a sound to be played in conjunction with the splash screen.
These ideas might be a bit overkill in terms of where you're trying to go with this. I tend to be a tweak junkie and like to see how far I can go to get something to look just right. I'm just tossing my ideas your way because I'm genuinely impressed with your work so far and would like to see this project continue to develop. Great job so far!