I've been using Flips over night since I've started cloth... with two prefolds tucked in that seem to hold up for eight hours. Have to get up after that 'n change him, but that's pretty good, I think.
With all these mentions of inserts, I feel like a cheap ass! Just got some inserts a couple days ago (the stay dry), gonna give 'em a go at night.
You don't have to use bamboo (although it is my favourite!). Do you have an organic Flip insert? Try that with a stay dry one on top.
I'm not sure, it depends on the baby really. Microfibre tends to leak when it's compressed so if LO stays still for a long time, it might leak more than a natural fibre insert would.