My son has a wide foot and Shimano's seem to be wider for a given length than other bike shoes sold locally here such as Pearl Izumi's which I have. I think he also has the xc70's and they apparently fit him very well.

Why are you wanting a stiffer shoe? That just makes you walk funnier. If you are competing, you might need the slight edge that better power transfer gives. But for fitness? However if you think your old shoes were so flexible that they were causing some pain issues while pedaling, then you've got a point there. But will you be mashing your pedals as hard on the road as you were when mountain biking off road?