I'm not an expert by any means, but i have been using wool at night with my daughter (now 8 months) since November last year and have never had any leaks.
I'm a poster on Cloth Nappy Addicts, and November is Buy Britsh Month, and i saw a lovely soaker that a WAHM had made and in my curiosity, i bought it. It was the best thing i've ever done. I was struggling at night, using well boosted Little Lambs and a Mother Ease wrap, and my daughter was wet every morning, so i thought i had nothing to loose, trying the soaker. She then went on to make me another soaker and a pair of longies to my daughters exact measurements. I'm so glad i did - i'd never go back to PUL wraps at bedtime now. It came ready lanolised and ready to wear, and no kidding, my daughter had it on every night sice i got it, until about a week ago when i got some Longies, which i use for nighttime now.
I'm not sure of the science behind it, but the wool works really well - i'd take it off her in the morning, leave it air through the day and then put it back on at night. As long as it doesn't start to smell of wee - that's when you know it needs washing and lanolising again.
The WAHM i bought of is Tempestous Poppet, and i can't reccomend her enough - she sent me some really useful information on how to care for and look after my soaker and longies, and is always happy to help - she's even given me very basic instructions on how to re-lanolise ect.
I'm not sure if i've helped any here - probably just waffled - but if there's anything i can help with, just shout!