In reply to dek:
There's an entire school of theory that kettlebells are more functional than dumbells in the sense that the weight is directional and thus more akin to situations in real life where loads are often off-axis, and kettlebells also have the added effect of improving grip and core because of this. One large kettlebell exercise (like a swing) works more muscle groups than the same movement with a dumbell, improves ballistic movement and offers a really good cardio workout if used correctly.
http://news.menshealth.com/why-use-kettlebells/2012/02/29/
To quote the main points of the article [in reference to kettlebells V. freeweights]:
"'If your goal was just to get strong, you don’t need kettlebells,' Brown says. 'If your goal is to burn fat, increase power endurance, and get strong, then kettlebells are a great tool.'"
"You’ll activate dozens of muscles instead of just a few, which increases your body’s fat-burning metabolism, Brown says. You’ll also improve your power endurance, or your muscles’ ability to repeatedly perform fast, powerful movements during an extended period."
That sounds perfect for bouldering improvement, or so I'm thinking?
Basically I still have the kettlebell from a previous workout I had intended to do very shortly before I had touched a climbing wall for the first time. I was more interested in whether I could get any real climbing-beneficial use out of it rather than the comparison with other weights.