Sorry, No answers only more questions in this response. :-(
I am equally curious about the answers.
My understanding from the Telus will it work thread is that 3G UMTS 850/1900 bands are required.
To add confusion, the SG3 wiki article suggests that all SG3 models support these bands
weblink is en.wikipedia.org/wiki/Samsung_Galaxy_S_III#Model_comparison_table
Now there are more questions on the table....
Do you want i9300 for its Europe support despite old quad core processor, and lack of LTE?
The i747 model with its newer dual core processor should get better battery life with LTE disabled.
The T999 model also supports 850/1900 with newer processor (removes Europe+LTE), but adds 1700 AWS for use on Wind/Mobility .
Would this model also work on Telus?