Since Shaw throttle traffic, you can prevent throttling by encrypting the packets. I use usenet a lot, and I subscribe to usenet servers with SSL, when I download large files like Windows 7, I can pull the files at 18Mb/s for about 3-4 min, then constant at 8Mb/s when the modem caps kick in.
I just have standard high-speed, can't justify to get Xtreme-I. If I get higher-speed, I will most likely will be adding another 2TB storage into my 2.5TB system already.
8Mb (megabit) is constant.
Usenet is my favorite because it is not monitored by Shaw at all. I went over 80GB on usenet and the usage wasn't even registered on the usage log.