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The stolen shares are, in most cases, far above.. NOT below the current difficulty. Think about it. If you found a share that was hundreds of times the current difficulty, wouldn't you want to save it ?
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Lulz no idea what you been smoking to confuse you, but a share is only worth the value of the work it was generated for, and a valid block share is only worth a block no matter what difficulty it is (as long as it's a block).
... and if a block is not submitted immediately, it's worth nothing if someone else finds a block while you procrastinate, so no you wouldn't save it - that's stupid.
If a share is worse than the requested work difficulty, it's worth nothing.
If a share is better than or equal to the requested work difficulty, it's only worth the requested work difficulty.