OK this is an answer for the yeti2 slim bearing question, because steves answer is wrong. shorter axle will not work, the bearing seat sticks out too much, a slim bearing in the yeti2 cant screw together all the way - ive tried. yeti2 would make a great throw for 4A, if it could take a slim bearing.
Very good point...I hadn't checked that since I didn't have a Yeti handy at the moment. Thanks for letting us know! -Steve