Feedback in DC to DC converter?

[carpenter]

I design DC / DC converter, see Figure.
Power consumption ranges from 0.1 W (Sleep) 0.7 W (Run) over to 14W while the heating.
I can not decide how to deal with feedback.
The first option is through the Zener diodes on the primary, the second optocoupler and TL431 over the secondaries.
It seems to me that feedback through the zener primary, smaller and more reliable in the long term (tantalum and ceramic capacitors)
Feedback with optocoupler is probably more accurate, but is based more on a LED optocoupler will have a limited life.
Question
What kind of feedback do you recommend and why ?

 

[enren]

This is my humble opinion as an embedded system engineer (not analog designer).
I would go for the Zener because less components are used so the implementation is simpler
hence a more reliable, smaller and cheaper circuit.
Also the power range does not justify an octocoupler.

 

[carpenter]

Thank you for your opinion, I evaluated similarly