I've seen this question asked a lot and the conversation seems to go the same way every time. There's conflicting information in game crunch, with a bunch of weird implications, and no official ruling on the correct interpretation.
As a GM this is how I interpret the intent, not the wording, of the rules.
1) Persona as Icons, when jacking into a device, merge with the device's Icon but don't replace them. So if a device is part of a PAN and a persona jumps into it, the device is still part of the PAN. A Living Persona cannot be part of a PAN on it's own because it isn't being generated by a device, but if that Persona jumps into a device that is part of a PAN, now that Persona is as well. Similarly if a rigger jumps into a drone slaved to his RCC, that drone is still slaved to the RCC.
2) The importance of merging the Persona's Icon and the device's Icon is that some Matrix actions don't work against Persona specifically.
3) It wasn't intended for players to be able to arrange their ASDF array to favor attack, sleaze and data processing, then hide behind the superior firewall of a cheap commlink. In fact, I'm pretty sure the confusing language about Persona's and their place in a PAN was meant to close the door on this idea. You know, that whole "can't have your cake and eat it too" schtick.
4) That said, let players slave their decks to comms if they want, just don't let them use their attack or sleaze while the deck is slaved.
As a player I wouldn't try it, Matrix rules can get convoluted if your try to enforce or abuse their exact descriptions. And they will. And suddenly playing a hacker will be much more of a headache for everybody.