Frostman
Pebble Pounder
The new Vaterra Ascendor uses a system similar, in that the cup side of the CV driveshaft is incorporated into the pinion shaft as well. However, the Vaterra pinion gear bolts onto the input shaft. The bolting of the pinion gear looks to be causing an issue in the Vaterra though. The square keyed piece on the back side of the gear looks to be causing a stress riser. I broke my gears in the axles last weekend actually.
The Axial version is a nice one piece design, and they are using CNC cut gears in the box which is awesome. I suspect the gears in these will be pretty strong, but I have never dealt with this level of power in a car. I never owned anything running 6s on this size motor. So I'm anxious to see the level of abuse it puts on parts.
From running MTs with 6s power, 6s will break things. No matter how strong they are. Big 1/8 MTs like the Savage HP and MT4, that on 4s can go a long time without destroying the drivetrain, will go through more parts on 6s. Just because they can handle 6s doesn't mean they will last long on it. As big squid said in their review 4s should be enough for most buyers of the XL. I might run 6s once or twice for fun, but for regular running I'd stick to 4s in this truck.