It is (in theory) possible to take an average hashrate (and from extension, average amount of shares of some time) and figure out how much you can expect to make in the long run using the different payouts.
well, in the long run you'll get <7% more from proportional, that's what you can expect.
no need to take your hashrate or any imaginary numbers into account.
I would say not true for those with lower hashrates, but could be wrong.