What you described (i.e. more leverage) will only feel better until the weight gets heavier. Keep this in mind - if you have a longer lever (your back), guess what - the muscles that move that lever (i.e. extend the hip) have to work harder to move the same weight. You're creating a greater mechanical disadvantage by leaning farther over. This means more difficulty accelerating, more fatigue, and then ultimately less speed. It also means you're relying more on hip extension and less on leg extension, which means you're limiting the potential for vertical bar acceleration, not increasing it.
And yes, that higher hipped start will encourage the bar to bang against the thighs, and that is NOT, in ANY WAY, productive.
Many people will feel like this is a more powerful clean - but it's because they're doing the alternative (i.e. correct way) poorly.