You identified the mechanical consequences of the two options. But I think for at least some of us, the choice is more based on fluff.
IS the battle a realspace raid? Forget rules for a second; are multiple groups of Drukhari uniting for a limited time under a single leader in order to cross into realspace and lead a coordinated attack against a non-Eldar race for the purpose of acquiring slaves and other loot?
If so, you're realspace raiding.
In any other scenario, you're not.
Sometimes my DE Crusade(s) will work together- when it's in their best interest. Sometimes they'll fight each other over territory too. Sometimes a single faction will risk realspace alone rather than going as a raid because they want their activity "off the books."
As such, I would say MOST of the time, I'm just using patrols. But certainly by the time my Archon earns his rank as a master, he'll need to raid increasingly often to maintain his wealth and power, so at least some of my battles will be raids.
Edited by ThePenitentOne, 07 April 2021 - 05:18 PM.