Really noobish question
I see fence-only systems like the Veritas Router Table and I see miter slot + fence systems. I see the interaction the fence-only systems would have with the bit. The miter slot + fence systems make me wonder a little though. Some, like the Kreg table seem go to great lengths to ensure fence parallelism. Others, like the Benchdog table don't seem to concern themselves with miter slot-fence alignment at all - that fence can just lock down anywhere.
So which is it? Does the fence need to be parallel to the miter slot or not? When you're using a sled & routing stiles and rails, other than possibly as a depth stop do you even need the fence on the table at all?? A sled riding in the miter slot bearing a component to be routed might use the fence as a depth stop, but doesn't the fence still need to be aligned to the path of travel of the sled? If not, unless you reference your depth at exactly the same spot on the fence each time, aren't you going to get a different result?
Or, you have it so all your work bears only on the fence, do you even need a miter slot at all?
I'm just starting out, planning a RT purchase soon and trying to understand what's going on with all of this to get my head around what I need to buy. Any help is appreciated!