Rare indeed. Vertical chain detonations are practically impossible. You can go so far as damage the floor tiles of the level immediately above the explosion, but you go no further than that. And cyberdiscs only detonate on the level they were on. Their corpses on the other hand will drop down to the nearest available floor.
In which case, I would assume the central lift would be involved, as you can move blaster bombs up and down them with no trouble.
Rookie vs Blaster bomb.
1. Instant Boom! Enough said.
2. Can sometimes be collected in the field.
3. Can go anywhere in the field on the same turn.
4. A lot more portable than carrying a bunch of rookies in your pocket.
5. Cannot be interrupted by reaction.
1. Costs zrbite to build.
3. You've got to give these rockets a lot of space to move. Clip an edge too soon - and it's all over. i.e. it doesn't necessarily fall exactly where you want it.
4. Loot + Boom! Enough said.
5. Reuse? What's left to reuse?
1. Does not cost elerium.
2. Far more versatile. Can be rigged with a high explosive and other throw-away weapons.
3. Can by hired in bulk.
4. If the rookie survives, and isn't an outright vegetable, the rookie can go on to be a pampered veteran.
1. Can easily turn a hardened veteran into a gibbering mass after sending in the n-th rookie to his or her doom. Seriously folks, lose a rookie, lose morale. Do this too much and even your commander's going to panic (heck, even your tanks will start to panic).
2. The last-ditch armed explosive will not always fall exactly where you want it if the soldier is killed.
3. Much more limited than blaster bombs in terms of mobility.
4. Cannot be collected in the field.
5. Opportunity fire can be a real problem.
Personally, I find it better to save the rookie and waste the blaster bomb. Cheap though rookies may be (relatively speaking, of course), I don't find the morale loss to be particularly desireable. Fear can really render the strong useless (in this game).
NKF, narrow minded fuddy duddy who refuses to let go of the past and will not accept anything newer than 1979.