[cherrylandcafe]

What must one consider while selecting dilemmas for one's pile?

I read there are "walls" and "filters". I'm guessing walls stop everyone, while filters stop selectively?

What are the drawbacks to dual dilemmas? Surely there must be some negative, else wouldn't we use those exclusively?

[Danny]

I read there are "walls" and "filters". I'm guessing walls stop everyone, while filters stop selectively?

This is correct

What are the drawbacks to dual dilemmas? Surely there must be some negative, else wouldn't we use those exclusively?

Dual dilemmas tend to cost 1 more than their planet or space counterparts that do the same thing (e.g. Casualties and Charged-Particle Precipitation).

There are also some cards that apply a carrot and stick philosophy to using different types of dilemmas. The Stakoron missions for example, make dual dilemmas more expensive, while The Conscience of the King makes planet and space dilemmas revealed cheaper.

If there weren't drawbacks to using them, or positives for using the S/P dilemmas, then you're right, they'd probably be used exclusively.