Push always with Q when you can
Master yi have a great damage and you can use it in jungle but with other build.

Pros:

So speed - Moviment and Attack Speed
Hdra+Statikk = Holocaust

Cons:

If you don't buy an item who give you HP
"The Black Cleaver" + Items with Life Steal you die

You can be a good jungle... Q engage is so good and R is a perfect spell for chase your enemys

In late game Yi with his Q is good in farm, but try always to hit your enemy