I like Softbums at night because my other night diapers were so BULKY I felt bad putting them on. In my experience, Softbums can work at night IF the diaper is at its full absorbency (maybe 5 or more washes) and you double up on inserts. I use bamboo inserts only at night because the combination of my toddlers night urine (more acidic) and the long period the diaper was worn started causing ammonia buildup, ugh. My baby has no issues with softbums at night and so I think softbums at night might be only for babies, not toddlers. Currently I am looking into getting a wool wrap and just laying in my softbums inserts for night. The wool and bamboo should give a nice breathable/absorbant nighttime diaper. I will update after I have tested it.
One night after switching to Softbums, I decided to use my old nighttime diaper, a bumgenius with both doublers. My poor little guy was SOAKED halfway through the night, I also tried a disposable and he soaked through that too. I take forgranted that with my Softbums I've got about 9+ layers of ultra absorbant fabric in the wet zone. The Bum Genius is only 5 layers and bulkier and the velcro is lousy...
When choosing a nighttime diapering system I think in terms of layers and absorbancy.
If you have leaks at night and the inserts are completely soaked you need more layers. If you have leaks and the inserts aren't completely soaked, you need more absorbancy in the pee zone, more layers in the pee zone, and/or you need a fabric that absorbs more quickly for the top layers (ie bamboo over hemp...).