Here's a review of the Slim Gaillard Proper box set I did for AAJ; there are reviews there of the Tatum and other boxes as well. . . .
http://www.allaboutjazz.com/php/review.php?id=10872
I've had this one, and I have the Wills, Milton Brown, Hillbilly Boogie, Wynonie Harris and Swing Tanzen Verboten boxes. I haven't listened to them much. . . .They're cool though.
I wasn't crazy about Proper at first, because with artists such as Pres and Hawk they weren't putting entire sessions into the boxes and I was just worried that material would become orphaned and forgotten, or that people would pick up the Pres box and think they didn't need to get anything else. . . . I've been won over by the boxes they have released that are more complete, such as the Harris and Brown and a few others. . . .