What is your goal with this upgrade? Are you "Just a rocker?" (It's OK, I am too, at heart!" After all I left music school to move to SF with my band!!!)
If you want a rig that's gonna bump, sure, go for it. If you are interested in reproducing accurate sound, there is a whole other world out there. A lot of good gear can be had for the cost of a $2000 pair of speakers!
Please understand, its not my desire to knock your choice. Its your ears and your ducats. My experience with DefTech, though, was... unispired.
I'm a chef, and the best analogy I can come up with is from the wine country: you go to the store and see a low cost brand like turning leaf, claiming gold medal awards from wine competitions... for what is quite mediocre juice... but the reason they stand out from the crowd is that after tasting 20 wines and your palette is fatigued, you get this wine with a touch of residual sugar left in after fermentation was killed off. And when the judges look back over all the wines they tasted... what stands ouT?
The one with powered woofers. (And yes, that T was intentional).
I would surmise that a large part of their cost is putting amps and passive radiators in every speaker. Not to mention the up-firing atmos module, which is not super effective if you really want to have good sound from an atmos rig.
Conversely, for the retail cost of two of those Def Techs, you could get two SVS Ultras and a PB3000 and be blown away by the sound difference. I'm not trying to sell you that either! Just putting a counterpoint out there for perspective.
Fluance Signatures get recommended as an excellent budget tower... add the matching Center, AND 2 PB2000 subwoofers from SVS for 2350.
Happy Hunting!