If you are a fisherman, definitely get the Outback.
You'll hear this advice a lot and it's terrible advice. And it usually comes from people who haven't tried fishing from both. I suggest you only listen to people who have, because according to every Hobie owner, their model is the best.
Not everyone is looking for the same thing when it comes to fishing. if you want a rock-steady platform with lots of storage, lots of rod holders, and don't care if it's slower, don't care if it paddles poorly, don't care if it handles rough water badly, and don't care that its harder to push along (on land and water) then yes, look at an outback.
But the Revo is a highly capable kayak for fishing. I have owned both. if I had to choose again I wouldn't dream of getting an Outback. Why? because it handles the kind of water i fish a lot better. And it's an excellent fishing platform in its own right.
Look guys, you can modify just about any hobie kayak for fishing. But what you cannot modify much is the ride. You NEED to buy a kayak that is well suited for your usage scenario and that includes water conditions. In fact, thats the most important thing.
Asking questions like 'which is better' will only get you a deluge of conflicting responses. Go and try them out. Spend some time in them. Think about how they suit your needs and make your own decision.