So before I had purchased the GGS screen protector for my 5D, I initially purchased the pop-up screen protector above. Before I had found the GGS I had seen this used over at CheesyCam and had plans to take off the doors and put my LCDVF magnet onto that. Well plans changed as soon as I found the GGS, but had already ordered the pop-up protector.
Now that I have received it, I am planning on keeping it just to use when I am out on the field and do not need the viewfinder. So when it is bright out the pop-up screen will add some shade over the screen as well as some protection from scratching. Probably another good buy for under $20. I was actually able to try it out today in the sun, and it definitely makes a difference in viewing the screen.
So if you got that extra $20 protect your investment and get one of these multi-purpose protectors.