I'm on extreme plus (25Mbps) and have definitely been getting higher speed tests, but I don't think actual performance has increased.
Speed Test #89976676 by ***************
Run: 2010-06-23 22:51:04 EST
Download: 39827 (Kbps)
Upload: 1006 (Kbps)
In kilobytes per second: 4861.8 down 122.8 up
Tested by server: 56 java
User: Eluder @ ***************
User's DNS: rogers.com
Compared to the average of 56 tests from rogers.com:
* download is 179% better, upload is 47% better
Speed Test #89976676 by ***************
Run: 2010-06-23 22:51:04 EST
Download: 39827 (Kbps)
Upload: 1006 (Kbps)
In kilobytes per second: 4861.8 down 122.8 up
Tested by server: 56 java
User: Eluder @ ***************
User's DNS: rogers.com
Compared to the average of 56 tests from rogers.com:
* download is 179% better, upload is 47% better