If you go on renegade's website under certified trainers they show the whole list...next to the name on some of them it shows a graphic that says "Kettlebell Specialist" email one of them and see what they think
I do know that kettlebells can become an "art form" after the body gets used to them, unlike med balls.
www.youtube.com/watch?v=79wi-vQ93hU
the above is a youtube video from one of John Davies Renegade Kettlebell DVDs...
And as always you can ask the trainer...