Another $5.99 T-Mo user here...

Unless you truly need broadband all the time, I don't think you can beat this plan. I get full http/https access, and the speed actually tests at about 100kbps down/60kbps up. (my last test was 92/55). Not blazing by any means, but certainly fast enough for email, chat/IM, and syncing calendars. This is on a regular GPRS connection....not sure what EDGE would do, or if the speed is limited by the proxy.

As mentioned, you must set up the proxy for both http and https, a process that takes about 2 minutes.

Also, T-Mo doesn't track bandwidth, nor do they charge for it. They also include FREE roaming on Cingular and Unicel (a huge coverage in the northeast) including their data networks which allow you to pass through to the proxy server.

Basically, it is unlimited use for 6 bucks...and for my needs it is perfect. If you need speed, though, you'll want to steer clear.