Hey, i've owned 7 female rats and 2 male rats and the females are definitely less smelly, though neutering a male really helps. My first rat lived in an aquarium tank and was constantly having respiratory problems. Now my rats are in a indoor aviary with plenty of climbing room, i've personally never had any problems with bedding being flung around. Cleaning really does have difference in smell though, my girls' litter tray is given a quick scoop every second day and their hammocks are cleaned every three days aswell as a quick wipe on the levels.
I currently have 4 rats in my bedroom and I don't notice any smell