@Joel: Have you ever had substantial success with training with a weight-vest? I would imagine that for example a 5 lbs vest was just annoying and not really adding much resistance. Don't know, maybe I should try it.
I personally had a lot of success with a weight vest while doing Joel's program in 2009. It really did it's magic. It doesn't make sense when you think about it, I was just doing some bad form bounds and stuff like that once per week with a weight vest but still it was great.
I think the harder overload in THAT particular jump does it's trick on the CNS level, although you can make an argument about depth jumps doing the same thing.