I can commisserate with you on this one. I have no problem with road shoes, but with trail shoes...oy vay!

My latest trail shoes are and Salomons, and while I do love them and they fit me well... the soles are too soft/forgiving and my arches hurt after an hour or more out there. It seems all trail shoes are soft (I've tried Brooks, Asics, and Montrails). I put my stiff orthotics in them, but they are still not stiff enough for me. I'm tempted to run in my road shoes, but they allow too much grit/sand in and then it causes blisters.

I hope you can find something that works for you...