Someone told me on OCTGN that the killing damage on a unit with Repulsor Impact field does not trigger its effect. I have not found anything to that effect.

Is this correct?

This is correct. The repulsor field is a reaction to the damage being placed on a unit. If the damage taken is great enough to destroy the unit, then the card won't be in play for the reaction. Also if you shield all the assigned damage, no damage will be dealt, so the reaction won't trigger.

Thank you for the response.

Yeah, you want to put it on something that has a lot of health. And only shield 1 or 2 of the incoming damage if you can.

This seems kind of unintuitive. I have a feeling a whole lot of players (including me and the people I play with) are going to get that wrong until they read about it in a FAQ or something.

Is the reason Repulsor doesn't trigger on the killing blow the fact that it's a "reaction" and not an "interrupt"?

This seems kind of unintuitive. I have a feeling a whole lot of players (including me and the people I play with) are going to get that wrong until they read about it in a FAQ or something.

Is the reason Repulsor doesn't trigger on the killing blow the fact that it's a "reaction" and not an "interrupt"?

yes, a reaction happens after its trigger. Interrupts happen before.