Satoshi's algorithm is much better.  If you switch away from weighting with the sum of difficulties, and go to the sum of log of difficulties, you introduce a new vulnerability into easily taking over the block chain.  That's because someone could make a very long chain of "difficulty 1" blocks and they could quickly be made to weigh more than blocks being created at the current difficulty n, because they are n times more difficult to create, but only weigh log n, which is a much smaller proportion of n as n increases.  All while difficulty 1 blocks will weigh the most in proportion to their actual creation difficulty.  So this idea is a bunch of nonsense, merely adds unwarranted complication at the expense of security.