I mean obviously a more powerful car is more likely to break things or cause leaks, but usually if something is going to fail because of too much power... it breaks. Leaks usually are caused by faulty seals or seals wearing out. Likely your leak is nothing more than a fluke. This is assuming of course the leak is at a seal or connection point on the diff rather than a crack.
Also, what makes you think the trans won't hold your power because your differential is having a problem?