Lumpy, given that your badges have only been the older square shaped ones, and the example you provided was the newer type, I think it best to remove anything you can. These badges are easily removed by sticking a paperclip through the hole on the inside of the case and popping the logo off. My personal theory is that H202 of any concentration is corrosive to steel, which is what I think the later logos are made out of, and which causes a chemical reaction that dissolves the paint. FYI, I sampled a few of the old square logos and they are most definitely made out of aluminum which is neutral to H202. The inlaid apple-shaped logos I've sampled are too dark a metal to be aluminum. Most likely steel. Remove them, either way – better safe than sorry.
Also, Target stores offer 1 liter bottles of 3% H202 for US $.99. Walmart, K-Mart & Costco likely offer similar values.
One thought about dunking large items such as the rear case buckets of the compacts: the buckets themselves contain a large volume, which on the inside does not need to be de-yellowed. Take a plastic tuperware-type airtight container as close to the shape of the inside of the case bucket as possible. Fill it with water and place it inside the larger plastic container you're going to immerse your Mac in. Then add the Mac over it and fill the container with H202. It will take a much lower amount to cover the Mac since the water filled container beneath the Mac will displace a much larger volume of solution. This provides the advantages of the more evenly distributed low percentage solution and the low-cost of the gel.