How to apportion ownership in a business entity split 2 ways.
Jurisdiction is Canada. 

A business entity will be formed with two partners. Whether additional
partners join in later is unknown. The entity will definitely *not* be
a general partnership with its Unlimited liability downer.

 
Before getting into the choices of limited liability structures (e.g. Corp, 
LLP, LLC, some of which may not even be available in Canada) one question.

If the partnership/ownership is split among the two founders is it customary
to go 50/50 or 51/49?  Obviously 51/49 is "nearly" even but does
provide for avoidance of deadlock in the event of disagreement.