I have an Ivanko, along with the CoC #1 & #2. Closed the #2 twice a few months ago. Got lazy lately, don't do grip stuff much anymore. Ivanko is nice, but you need grip tape in order to avoid your hand slipping on the slick, metallic handle.
Nate, how do you advise training grip? I think I've heard you advocate singles or doubles, low, low reps. Thing is, if you get the CoC #1 for a single or double, let's say, there's no way you can get the #2. I know Beast used to rep them for about 15-20 reps, and once he hit that, he was usually able to get a few reps on the next gripper up.