I recently did a bit of swapping around in my RC garage in terms of cars and my current lineup is the D413, the RB6, and the DEX210v2. I had a DEX410v4 and traded it in for the D413 as I felt I wanted a car that could be more durable. So far it seems I've found it. Running Durango in Los Angeles is tough given the parts support is almost nill. Most of the shops no longer carry it. This is what led me to the RB6. I haven't let go of my DEX210v2 yet and have recently started to work on it and get it ready for my girlfriend to try out. In doing this and having recently built my RB6 I wanted to share my thoughts on the comparisons. They are both great cars. The DEX210 wins by a mile in tuning options though IMO. Especially when you look at 3 gear vs 4 gear transmission included in the kit, and all of the caster, and wheelbase and roll center options. I think the balanced slipper setup of Durango is better than the rest as the spring is opposed to the slipper pads. This helps offset the weight of the slipper. I've upgraded my DEX210 with the Exotek suspension hanger allowing me to quickly adjust anti squat. I think Kyosho wins in the rear end adjustment area though, especially if you upgrade to the Offset bushing alum pivots. This allows for rear width adjustment at the inner hinge pins along with toe in and in stock form anti squat is adjustable with shims. The DEX210 does have a wide array of adjustments in terms of LRC and HRC setups, and these don't require axle changes like some of the RB6 setups can. The Kyosho setup changes can require a lot of optional parts.
Lastly, I think the Kyosho shocks are better than the Durango (sorry Durango fans!). They don't seem to weep as much and I've found the screw in type that Durango uses can break the pistons themselves at times. I actually picked up a set of MOS coated front shocks and a set of machined taper pistons to see how these compare.
All in all I still love my DEX210v2 (honestly the DEX410v4 is still awesome) and I'm not sure I will sell it just yet. All depends on what Durango comes out with next. I'm sure whatever it is it will be awesome.