When the 9mm/.45 debate began both rounds were loaded with round nose bullets. The debate should of been concluded in the Phillipines, when the US Army dropped the .38 Long Colt in favour of the .45 due to the number of American Soldiers being hacked to death by Moro warriors who had been hit solidly with .38 bullets.
Since then the debate has been muddied up by all sorts of techniques devised to make bullets expand. Some of these worked pretty well while others did not. I remember shooting 158 gr. Sierra hollow points in a maximum load from my .357 and the recovered bullets were for all intents purposes unchanged. In a more practical example, I heard from a reliable source that Federal Hydra-Shoks failed to upset when the nose cavity filled with material from heavy outer clothing, yet these bullets gained a good reputation when used in warm climates and the recipients did not wear parkas.
I have concluded from my own tests that a 9mm will out penetrate a .45, but this is of little advantage in the defensive HG, and is a disadvantage when viewed from the basis of liability in an urban environment. The FBI established that penetration of 12" was necessary to produce the desired effects in tissue. Beyond that, anything which can be done to improve the 9mm can also be done to improve the .45.
When we look at the history of defensive shootings in Canadian Courts two things stand out. One is that if you are using handloaded ammo you loose, because under the law to handload ammo is akin to premeditation. The second point which stands out is that if you use hollowpoint ammo, it is percieved that you are attemting to due more than reasonable harm to your attacker, so again you loose. With these historic gems in mind, I would suggest that in Canada the best defensive load is a .45 Auto loaded with round nose factory ammo.