I do. Have a 7+ and an SE. It's the perfect setup...well at least the way I have it set up:
I have a T-Mobile DIGITS 2nd SIM (cloned to my main line, free since I beta tested) in the SE. I have the SE's number (which I don't use) hooked into iMessage (my main 7+ number). All iMessages are in sync with the two phones (and my iPad/Mac) so I can grab either one on any given day and everything is in sync. Phone calls ring both devices and outgoing caller ID shows my main 7+ number (that's the point of DIGITS).
I also have an Apple Watch...paired to my 7+. Obviously it can't be paired to two phones at once, so I did a workaround:
Started the hospot on my SE, connected my 7+ to that hospot. That saved my SE's hotspot to the watch. Now, when I leave the house with only my SE, I can turn the SE's hotspot on and my watch connects to the Wifi, just as if it was paired to the SE.
All of this may sound convoluted, but it works perfect for me. Two phones, two lines all for $70, tax included.
Love it.