Are there any disadvantages to dispelling demons as they spawn from Fade Rifts?

Solution 1:

Most of the enemies that are spawned from Fade Rifts don't drop regular loot, but they do all drop research items. Dispelling enemies before they're active means you won't get those at all. The research items are used to unlock Codex information, and even a damage bonus against researched enemies, so using Dispel throughout the game, especially to prevent the bigger enemies' appearing, can leave you a bit weaker against rifts by the end.

Solution 2:

The only downside to dispelling demons is that it generates less Focus than if you fought normally and, optimally, performed some cross-class combos on them.