I like this idea a lot. As a small dog owner, I know very well how different it is when taking care of larger dogs compared to smaller ones. Larger dogs require much more exercise and play time than smaller dogs do. And for me, it can sometimes be more difficult to care for larger dogs since I live in a smaller-scale apartment. This would definitely incentivize and motivate sitters to branch out and be able to take care of dogs of all weights and breeds.