The motive is entirely political. People didn't want the trouble of switching their clocks ahead in April and back again in October. They are (again) talking about changing the rule to go along with the rest of the continent, because businesses who do business internationally find their customers are confused. Let's face it, it is confusing. April to October, they are one hour behind Manitoba, but on the same time as Alberta. October to April, the situation is reversed. It makes it confusing to try and call your friends in Saskatchewan (I used to live here), because you can't always remember if they're going to be asleep/awake/home from work, etc. Of course, if you ask any Saskatchewanian, they will say that the rest of the country's habit of changing clocks twice a year is stupid and silly.

what benefit is derived from moving the daylight during the Summer.

I guess it's not just the summer, but as I said above, April to October - half the year. During the longest days of the summer the sun is up from 5:00 am to about 10:00 pm (Daylight Saving Time). In standard time that is 4:00 am to 9:00 pm. Similarly, in the winter, you only have about eight hours of daylight. I guess we shift back so they'll be centred on noon. In practice, on the shortest days of the year, the sun is up from about 8:00-4:00, depending on your latitude and where in the time zone you live.

Notice that say, Sydney, Australia is only at 30°S while St. John's, Newfoundland, Canada is at 47°N (and this is among the less-north parts of the country - it gets more drastic as you go more north). The relationship between latitude and daylight hours is non-linear (goes as sine(latitude)) so we get a lot more variation in daylight hours that in Australia.

If you have no idea of the layout of our provinces, try this link and choose "Canada Political": http://atlas.gc.ca/english/quick_maps/index_quickmaps.htm

Aren't you glad you asked?