Lightweight does not necessary mean there is a compromise in stiffness, durability, functionality or safety!
The Carbon-Ti X-Rotor is one of those amazing products which is not only lightweight, it also increases performance all around!
I am using the 160mm rotors front/rear on my Epic bike, 180mm rear on my trails bikes (unfortunately Carbon-Ti has no 200mm, which I would need for the front) and 140mm front/rear on my Crux Cyclo Cross bike.
The performance especially the cooling is much better then standard rotors, so as I have not experienced squeaky noise. Very impressive is also the durability. Even riding it consistently for more then 1.5 years my trail bike, the pats have not worn it down at all, where a normal rotor very quickly wear down.
Weight X-Rotor is around 77g vs Sram 105g. So the total weight safe is around 56g for 160mm diameter. It might seems not so much, but it is almost a fourth less then a standard rotor with better performance and I believe the price of euro180.- is well invested since also the durability is way above average!