While I admire the principle in some ways, why would deciding to become a martyr make an important difference?

Both took a courageous step in leaking documents they knew could lead to their execution for simple moral convictions. That alone makes them more alike than not to me.

Chelsea Manning and Reality Winner both accepted the consequences, by that measure. William Binney attempted to go through channels, with little success.

Snowden (veteran though acting in a civilian role) has had far more impact.

What Ellsberg and Snowden both managed to do was to make the story compelling and the information unescapable.

Consequences (your argument) or civillian status (raised elsewhere) are both exceedingly red herrings.

lol, there is no difference. They both did things that benefited the public and should be celebrated for it. There is no "but". The military state has goals that are not aligned with your well being and making moral choices based on what the killing machine declares secret makes no sense.