Your text above says "especially since the G5 can receive both VHF and 800 P25" Technically it can receive one or the other, not both.
If your a member of 2 different FDs then you should have 2 different devices to monitor each.
Its great you personally want to carry 1 device but at any given time traffic can be on 1 device and you will significantly increase your chance of missing traffic on the other. If both are mission critical then you need to dedicate a device for each.
No matter how well a device is built, it can only pass 1 audio path at a time. So trying to monitor two is an unreal expectation.
I saw a pic of a local FD on scene of a fire. The IC had a speaker mic on each shoulder. 1 for dispatch and 1 for fire ground comms. Sure his APX can do much more then that but he realized the devices limitations.
Not the best example but if you get a bad storm up in your area both towns will be affected around the same time. Traffic will increase on both and you will need two radios.
While that may only account for a small portion of time you would need two, it doesnt negate that you want to make sure you get traffic on two different departments on different bands.
But your a subscriber. You are a member of 2 FDs. I am a listener and not responding to emergency calls. So for me id love to see them scan across systems.
This was brought up in another thread. The statement "if they have a radio then they wouldn't need our pager" was made by a person affiliated with Unication. It is an inaccurate statement because there are most definitely times where monitoring multiple talkgroups/frequencies can be beneficial to the end user. If it is mission critical, backups and redundancies need to be in place. The Unication pagers are a great tool, but only a small part of a bigger picture.