I've got two of the XL's, one on a driver, one on my 60 wedge. A full 3/8" bigger than a "standard" grip, my fingers juuust touch my palms when I wrap my size XXXL hands around them (I can hit Caps Lock and the Enter button at the same time with one hand). I also notice that I don't flip my hands with the wedge, just glide through nice and easily. I've got the other grip on a VS339 stuck in a 6 TK1 head, that seems effortless to hit, but it's now too low lofted for me (My swing speed has dropped by 20+ mph over the last 6-7 years).
My gamer set of irons has Lamkin Permawrap Jumbos (+1/8") with 8 extra wraps of buildup tape - not quite as big, but close. Also, as an experiment, I took a Karma rubber grip, and kept putting wrap after buildup wrap on the shaft.... was still able to get the grip on easily after 12 wraps, I could probably have gotten close to 20 wraps if I'd stretched it a bit more.