Montreal are undefeated this season, except for their loss to the BC Lions, while Ottawa are 4-6. In their last game at Commonwealth stadium they received a drubbing 57-16 at the hands of the Eskimos and looked completely outclassed on both offence and defence. I don't expect to see much improvement when they host Montreal.
While the 10 is not such a key number as in the NFL it may be too much to lay. I took Montreal -9.5, it is still available.