This question is mostly aimed at @creatorlars but happy to hear the opinions of others.
Why did you make the switch from 1.0V to 2.5V on the VFS pin of LT1251/1256 circuits?
Is the non-linear response near 0V of the LT1251 the reason?
Or was it just due to the ease of buffering a TL431 reference voltage?
This old circuit example below used to reference the VFS pin with 1.0V but now all of the Cadets reference it with 2.5V. It seems like adjusting the gain of any control voltages up to 2.5V is more complex than it needs to be.