If you come over, you'll find most of my daughter's stuff is green. Most of my son's stuff is black, mine is red, and my husband's is blue.
In the morning when we're heading out the door, it's easy for my son to grab his backpack, black water bottle, black lunch box and be out the door. Same thing for my daughter. It has significantly minimized the number of "I grabbed the wrong thing" episodes and makes for less stressful mornings for all of us.
I'm not saying buy all new stuff. Just as you replace, keep it in mind.