^^
FZS Mileage --> 35-40 KMPL 156cc stressed engine.
RTR 180 --> 50 KMPL
For me
FZS is like a fashion accessory. U'll have to replace it if something better looking gets launched in market or u'll look stupid riding (Wearing a classic Amitabh Bachchan hairdo). coz FZS is mainly for 'show of' purpose. An enthu will know that 140 section tire is too much for a small 150cc 2 valve, carb engine.
RTR you can have it for years and look cool for maintaining a performance bike that u love. Vibes have reduced too. u can get rear disc brake with carb engine. Looks good too, better than Pulsar, Uni, CBZ X (yuck!!).
No offence to any FZ owner. Just my thoughts.