So... When you fail a guts roll you need to move towards the best possible cover for you. What happens if, 1" away ( IE: Fully in range of your guts movement), there is a cliff. Or the side of a building. 10" tall. Thats the only way you could possibily move to have cover, there is nowhere else 2" away that would give you cover from the attacker. Do you have to jump off?
No, Guts movement follows the general movement rules so the trooper's base must always be fully supported, you can't jump as Guts movement.
It's never possible to guarantee that you can survive a fall (OK, except maybe a Jotum). But no, the only way to fall is to jump, and you can't jump as part of a Guts move
Guts Roll movement has to use a Short Movement Skill. Super-Jump would enable you to jump off the cliff while Climb+ would enable you to get over the side to hang on for your dear life.
but only if doing so would give you total cover, as your silhouette sticking out sideways, if visible, is never in partial cover.
Sorry, maybe I'm being blind but where does it say you use a Short Movement Skill, I thought it was just a 2 inch move?
Yes. This is true and important. Sorry. I'm remembering Dodge. The two effects are far too similar to each other :(
@Wyrmnax For what it's worth - Guts Move doesn't get halved by being Prone (since that only halves your Profile MOV values) and while it's not a cliff you can fail Guts to go Prone and crawl down a Ladder if you can gain Total Cover from that. This works because ladders allow regular Movement in vertical direction. Just bringing it up it since you mentioned buildings. As a follow up to what @Mahtamori said. Unlike C+, Super-Jump doesn't let you jump with any sort of Movement thus can't be used for Guts Movement.
Can't be prone while on a vertical surface though "Troops can never be in the Prone state while they Climb or hold on to a vertical surface" From the climb rules
That is only the case for Climb. Ladders specifically allow you to use a good old Move instead and work the same ways as stairs. Using a ladder is also not "holding on to a vertical surface" in the terms that Climb refers to and you can ARO just fine while on a ladder. REMEMBER A figure in the Reactive Turn who is holding onto a vertical surface cannot ARO. The reason for this is that, while on a vertical surface, the only available Skill is Climb, and Climb is an Entire Order that cannot be used in Reactive Turn.