Hi Louis,
To answer your question about writting on any exhibit, if you send them to SGC the best you can expect is a 30 if its only a tiny bit of ink writting or erased pencil on the back. Any with more ink and up will get a 20. PSA handles them different in that they will grade the card then add an MK qualifier to it. Based on the cards you sent me condition wise you would be looking at any where from a PSA 2-5 (MK). From a selling price stand point it will not make a lot of difference, nearly all the PSA registry folks subtrack 2+ from any card with a qualifier and many just will not buy them.
Here is an example of a 27 Exhibit Cobb with the word "old" written on his sleeve. I had this card crossover to SGC from the PSA 3 (MK) it used to be.
