The radiator on the DT's looks promising for added depth and healthy output, though I've never heard them, I doubt you could go wrong with them.
Another brand to look at costing about $700 pair. Speakercraft Oe-8, three way design, 1", 2.5", and 8 " aluminum drivers. Never heard this one either.
I've compared and contrasted three outdoor speaker products, each with 6.5 inch midwoof:
-Polk Audio Atrium 7 $399
-Axiom Algonquin $378
-PSB Cs1001 $550
The Axiom delivered the most bass, but didn't go quite as low as the PSB and Polk. Unforunately, it is the worst speaker that I have ever owned. The PSB could output louder bass than the Polk, but they both were pretty equally in terms of the depth. All of the speakers output frequencies in the upper 40Hz range at fairly healthy volume levels.