I am a T-Mobile customer using the SDA. I just bought the Blackjack five days ago. I like it so far, but the battery life has not been very good. I can't get more than 30 hours per charge using Direct Push set to notify me as soon as new email arrives, talking for less than 5 minutes, and surfing for less than 15 minutes. The responsiveness of opening and running programs seems a tad bit faster than the Dash, but I only used the Dash at the T-Mobile store. I am thinking about porting my T-Mobile number over to Cingular, but didn't want to do it without giving the Dash a chance, which may have a much better battery life. 3G on the Blackjack is great. But as far as necessity ... I guess it's not REALLY necessary. I am looking forward to MobileTechReview's reviews of the Dash/Excalibur and Blackjack. Keep up the great work.