There might be a difference between actively using more than one of them at the same time or simply having them connected to your network and having your network passively taking advantage of their matrix attributes.
There might be.
Then there might not be.
The Core Book doesn't have anything in it about creating a Persona in it, and it sure doesn't even mention anything about being able to use more than one device at a time. (Not even to determine your Matrix Attributes.)
If you’re a decker, your Matrix attributes are determined by the device you’re using to access the Matrix.
Emphasis mine.
Now, I'm not arguing the point, as
I'm aware of what Banshee's intentions are.
My point is that if there is any restriction on the number of devices you can be "logged into" at a time, and whether or not you
have to be logged in to benefit from the device(s) isn't clear.
Everything people think is true about those rules is carried over from previous editions only.