Nice to see a lot of action in this thread!
I'm using 4 DTS-10's now and have the Alpines in two of them and original drivers in the other two. I blew one of the originals not running a HPF.
For the poster asking about the inuke 3k vs 6k, definitely get the 6K the extra headroom of the 6K will help.
I'm currently using 2 velodyne SMS-1's, one per pair of DTS-10's. The main reason I'm using the velos is I can High pass at 12Hz and it has both phase and polarity adjustments. I had a hell of a time getting all 4 to play nice with my mains.
I've also used a minidsp but had output issues and with no phase control couldn't get things happy at the crossover section.