Ahh the horror of sore feet
I feel your pain Pebbles
I have also had significant problems with my feet and riding shoes. I also had pain in the arches, but also numb toes and it took ages to figure it all out. In the end I forked out for the Sidi's as well (I'm a mountain biker and wear the women's Dominator 5's) and it is true love. I think once you find a shoe brand that works invariably you should stick with it.
But in regards your feet - even though you are now back in Sidi's, your pain might be continuing due to some residual foot injury. Perhaps your musculature in your arch got a real bashing from those other shoes and just needs time to recover? It might be that a visit to a good physiotherapist or podiatrist is in order...
If you have sore arches you might want to consider heat moldable insoles that at least allow you to create insoles that form fit to your own feet - manufacturer supplied insoles generally suit few people. You can usually source these from your drugstore/pharmacy, or even from a good sports physiotherapist (that's where I got mine). The only challenge is finding ones that are narrow enough to fit in a good race shoe!
It may still be fit, but if you had no problems with your previous Sidi's and they have made no major design changes, then it's probably still just recovering.
Hope you feel better soon
GumbyGirl
Keep ridin' and smilin'....