have you looked at the New Balance 101 (9mm differential) or the New Balance 110 (4mm differential, same last as the NB WR10)?
Other brands to look at are Newton, Inov-8, Vivo Barefoot, Merrell. Try reading some of the reviews on birthdayshoes.com and se if anything fits your criteria.
Yep. No luck.
I seriously tried on almost every trail shoe in the store - mens, unisex, cross-country flats, you name it. I was actually going to just buy another pair of the Kinvara (road) but they're unstable through the arch on downhills...plus the store was out of my size.
"I never met a donut I didn't like" - Dave Wiens