SG recommends the krux frame for shorter torsos.
Sort of. During my discussions with them, they said that's only one of the considerations. More important is how it fits your back. The Xcurve fits the curve of my back much better than the Evo. Some individuals the curve may not properly align. Further, they recommended the Xcurve for my frame size and said that recommendation is more for individuals closer to 5' than 6' tall.
Also worth noting is my head hit the back of the Evo/Krux frame the same way it does the Xcurve. I just didn't mention it since I'm returning that one.