The Revo is a little faster, so has a greater range or, would get you to your fishing grounds sooner. It also would be more efficient against current, wind and chop.
Here's a photo review of the Revo -- you should have no stability problems with either, so it doesn't end up as much of an issue.
The side trays are nice on the Outback, however. By the way, if those are important to you, Apalach
prefers his (wife's) Sport to his Outback for fishing because of its light weight and maneuverability. If you look at his posts, you will also find a wealth of rigging ideas for both.
By the way, you can learn to use the Mirage Drive in less than a foot of water by operating the pedals in a flutter pattern near the hull rather than a full sweep.
Finally, if you shop for an Outback, be sure you actually get the '07 model -- it has some significant hull improvements!