I am not able to answer your question but I would like to share my experience with my endowment with profits policy. I held the policy for 20 years, initially the annual bonuses were acceptable, but they quickly began to fall, year after year. Eventually, I received a letter stating that the annual bonus would be reduced to zero, but that the terminal bonus would be increased.
The twenty years elapsed........ and due to adverse conditions the terminal bonus was also reduced, to almost zero.
The only thing guaranteed in these policies is the commission that you have to pay, that was never reduced.