Yes, I owned an HTC Touch Diamond for Sprint.
My overall conclusion was, it is not recommended for the faint of heart.
The Blackberry is a much more pleasant experience. But I will not recommend both the 8330 and the Tour because both are obsolete now, lack wifi and prone to sticky trackball issues. Not to mention OS 4.x has all these funny issues that OS 5 fixes, like having a software reset.
I would recommend the Blackberry Curve 8530, which is a great bang for the buck (600MHz Qualcomm processor, Wifi, OS 5.0, optical trackpad) or if you want to spend more, and just wait a bit longer for the Blackberry Tour2, which fixes the Tour's mistakes. The Tour2 has the optical trackpad, OS 5.0, Wifi, and appears more nimbler than the already nimble Tour.