Eh our faction focus was effectively nothing but them saying raiding force works still, so I gave it a day to think about applications. There are two big problems for it though. The most obvious is the 3 patrol isn't doable until over 1500 points since they set a detachment limit of 2 til then, so at 1500 or less we get penalized for using more than 1/3 of our codex, which is... not great honestly. The second problem is even at over 1500 points, it creates a rule of 2 assuming you don't run double kabal/cult/coven patrol, so its rule of 2 or lose1/3rd of our codex. While that is functional its once again, not great, as one of the ways we get around our fragility is redundancy.
The problems above aside, its not terrible, you can make a functional army with 3 patrols, that has a fair bit of versatility, but a 3rd more much more minor problem is it makes army creation far more rigid for us. Every army you build using all three factions will include 1 of each troop and 1 of each hq (or draz/urien). so ~ 300 points are locked, not counting the transports. Like I said not the end of the world as most of those units are all solid, but it does make army comp somewhat static. Honestly I don't think it will change much if anything for us we will still be able to run the comps we ran before, just by doubling on coven or kabal. Makes wyches slightly more accessible honestly though if we are willing to run just two ravs or flyers(of the same faction). Thats a pretty good thing, honestly as before our options to get a unit of reavers was bad CP or a heavy points investment in succubi and wyches.
Overall I'm am pretty neutral on it some good some bad, but we can do still do everything we have done before with some easier access to units that would have lost us CP before, so its fine. Still concerned about our fragile vehicles now having no advantage in exchange for being fragile based on current information, but we will see.