I wear a 12 EEEE shoe and bought size 13 Manawan's and got a perfect fit.  My feet feel like they are in a custom made fleece glove.  These slippers have a wide toe box  but I have really wide feet and these fit great.

I got mine at Gear X for about $48 delivered to my front door and worth every penny.  The sole will allow you to go outside and not soak up water like a sponge. Nor do they pick up a lot of dirt to get tracked back into the house.

I love these slippers.  I tried lots and lots of different brands on my feet but they  just didn't feel right.  These were a perfect fit right out of the box. I like to wriggle my toes and have plenty of room for my toes and these have that advantage.

After less than a year of use and mind you they are slippers not everyday shoes the soles are falling off.  The stitching has cut though the gum rubber sole and the gum rubber sole is falling off.  Sorel has a one year warranty with you paying the freight to and from for repairs. I would have expected the soles to hold up a bit better given the only outside use these have seen it to fetch the morning newspaper out of the driveway.

Update 4-5-2013:  I initially gave these slippers a low rating even though I loved the fit due to the short life of the sole material.  The replacement slippers have been in service for more than 2 years and are still in great shape.  I have to assume they had a problem with the sole material and got it resolved.  When these are gone I am going to buy another pair without hesitation.