For example, an SL X.A.30 build in Boost form weighs 1420g (per the Newmen site)
Where did you get the 1420gr number - homepage says 1325gr and my wheels are actually 1314gr.
I bought these wheels in july and still very happy with them. 30mm internal width allows me to run pressures 1.1-1.2bar even with light tires.
Hubs are well engineered and waterproof. I have jetwashed my bike multiple times during last 3 months and zero problems - dt swiss and other hubs cant tolerate washing and rain so well.
Ride is quite compliant - exactly as it says on homepage. Mcfk and duke wheels are much harsher.
Because I weigh 91kg I would say they are strong also - atleast for xc riding.
Probably I will buy second set for my wife but with sapim cx-ray spokes instead of d-lights - result should be under 1300gr and more aerodynamic.