So, I'm glad there's a rule about Edge abuse, and even though I also don't know how grenades and avoiding them work in 6, I know how they work in 5. Here's hoping all the ways to deal with them will be in 6 Core (and it sounds as if they will be).
Anyway, a thing I read here once is that grenades (especially high-explosive ones), when brought up against the Barrier rules, can not only destroy nearly every cubicle in its blast radius, it can also blow apart cheap walls and even flooring.
So the question of, "Do you really want to cause indiscriminate property damage?" will cause people to pack flash-bangs instead. Or just save grenades for the Really Dangerous Stuff.