In short, no. You can customize it til your heart is content, or at least I hope so. I have done similar things. I changed the academic pasteboard hat to a different one and use a different background in some of my logos. I have even added my hat on my Moodle to the F2 user default (aka smiley pill) for site branding.
I like to give credit to Moodle.org. but I have seen sites where you would never know it was Moodle driven. Chris