I'd think that as long as you make it clear that it will not damage the keyboard and you know what you're doing, he won't have a problem with it. I don't think it's really necessary for you to print out the whole wiki. The key models and numbers are fairly easy to remember and find on the boards. Just look for Cherry G80s and Model Ms. With the G80s, if they have an H in the model number immediately following the G80-xxxx, you know that they're double shots and you should offer the fellow something for it. The only ones that may be hard to pick out are the ALPS boards, as there're so many different brands. Take a look see for Chicony boards too while you're there. Those can be worth having as well.