You give the maus as an example.

There are plenty of places where most 3 character combos can rank at some risk for high reward. If you take Isildur's ranking list, I'm often in those places while a good ten ranks below his suggested rank range, and pulling in great exp for it.

If you want high risk and high reward, just start ranking in areas that you currently consider too hard for you because of your level. You get good exp, and the price is that it is harder to stay alive. However, a well organised (by which I mean everyone agrees on their role and keeps a cool head when things go wrong) group can handle things a far stronger but less organised group cannot.