I'll stay with the Atrix, I had a Captivate and don't get me wrong, the Captivate was a good phone, but the Atrix is so much better. Here are some of the issues I had with the Captivate:
1) bad lag problem because of the file system they chose.
2) GPS was sketchy at first.
3) System and User storage was not separate, which meant that upgrades (i.e. from 2.1 to 2.2) wiped out your applications and their data and settings.
4) upgrades were done through Kies, which barely worked and meant to upgrade, you had to connect your phone to your PC.
5) Battery life, had to charge every night and some times during the day.
6) Samsung was very slow coming out with upgrades. The Captivate is officially still on 2.2 where-as Atrix is on 2.3.4
Some of these issues were big ones for me and the reason I switched to the Atrix. I will not seriously consider another Samsung Android phone until they fix the above issues and how they deploy their updates and their OS.
I have really liked Samsung phones in the past, but my experience with the Captivate and some of their recent non-smartphones makes me steer clear of them.