Quick question that I was just thinking about. I'm wanting to pick up a second flash to use mainly for backlighting with and without some gels. I'm probably gonna pick up a cheap Vivitar flash for this. However, I don't want to lose my CLS/Commander mode abilities so...... Can I use CLS (popup flash) to fire my SB-600 while also having the cactus trigger on the hot shoe to trigger the background flash? Will the both work together?? I've never really heard of anybody doing this so I"m curious as to whether or not it would work.