You will not get power cleans anywhere near your bench numbers unless you can get your knuckles on your shoulders. Catching it in your hands defeats the purpose, and dimishes the value of the lift.
A power clean near 300 is sick lifting, indicative of a 500 bencher perhaps simply because of brute strength. But, I'm not so sure it translates into a heavier squat or more importantly a monster deadlift.
It's a power move, with all the fast twitch muscles firing full bore. How many of you pull a deadlift with your fast twitch muscles? I think Andy Bolton might, but how about you?
Unless, you're willing and able to go for a full squat clean, a power clean is simply a supplementary lift to introduce power (ie fast twitch muscles) into your typical static strength push and pull workouts.
In my opinion, Olympic lifts are great, but they simply add dynamic (fast twitch) strength to normal strength. The are not a panacea. They are supplemental.
Well, unless of course you want to be an olympic lifter. Then they are crucial!