Just to throw something completely different out there. Numb toes can also be a sign of sciatic pain and nerve issues. Out of curiosity, do you also suffer from any pain in your low back or hip, either during or after long rides? Does your foot ever feel numb when you're NOT on the bike?
I've had all manner of foot issues, including both pain and numbness. The pain, IMO, is largely a shoe issue. Especially in the hot summer months, I get a horrible hot foot and pain in my big toe. I've been to a podiatrist who recommended some custom orthotics. He put some temporary pads in my shoe, but they didn't really help. I think I may just need to switch shoes. Sidi's toebox may just be too narrow for me when my foot swells in the summer.
I have also suffered from some numbness in my feet. Loosening the straps on my shoes, new insoles and thin socks do help, but I also found some relief in doing the stretches--before, during, and after my rides--described here:
http://www.spine-health.com/wellness...ormis-syndrome
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher