The Inov-8 are known for their narrow heel. I find that they really hold my narrow heel very very well. In fact the OR Winter Show Inov 8 podcast on BPL talks about the fact that many women have fitted just fine in this "unisex" shoe although they are coming out with a women's line.
As far as forefoot I think they are relatively wide. I have a narrow forefoot and find the forefoot just roomy enough.
I think there are some online retailers who pay for mail shipping both ways. See the www.inov-8.com web site. Also REI carries Inov 8 and you could try and see there. I think all models fit about the same with the racing models snugger.