The algorithm you propose was heavily debated in the early days prior to BitShares 1.0 launching. I was originally supportive of the algorithm you laid out, but use Agent86 on bitsharestalk.org convinced me that approval voting was vastly supperior from a security perspective.

Under your model someone with 8% can guarantee they get one person in. Under DPOS it is highly unlikely that someone with 8% could get into the top on their own. In Steem the top witnesses have between 19% and 23% approval. That is more than any individual account except the steemit account which isn't voting.

If you adopt the 1 share 1 vote approach then the top 19 witnesses would each have only about 1% approval. With 51 slots they would each have less than 0.5%. It gets worse because the popular ones will end up with 2-3% while the less popular ones will end up with 0.1%.

In this environment, someone with 8% of the stake can come along and vote for 16 people with 0.5%. To make it apples-to-apples, someone with 20% of the stake would end up controlling over 51% of the active witnesses because they would each get 1% or more approval which would be more than the vast majority would ever get.

Good luck with your system. I am always happy to see new uses of DPOS. I am just sad to see backward steps that fail to incorporate the lessons learned.