My experience with SMS is that it doesn't conflict, but with SS it's not as useful.
In some ways it's very interesting, because SMS shows you everything in the settlement that can be assigned. Every bed, every plot, everything. However, it lists unemployed settlers as "unassigned," and if you assign a settler to anything -- including a residential plot -- they display as assigned. So you could have a situation where there are 20 settlers, 3 unemployed, and you won't immediately find them in SMS if they are listed as "assigned" to a residential plot. You'll have to go into each settler's assignment list and find the ones who aren't assigned to jobs.
That part is very frustrating. On the other hand, SMS is very useful when it comes to looking at all the things in your settlement that are assignable but that haven't been assigned yet, and I've had some success (though not consistently) in trying to unassign settlers assigned to caravans when I want to replace them with robots.