I can't speak for them, but I suspect that the Big Three do use other devices regularly; they seem to have a good grasp of the overall mobile landscape.
I don't know about Adam, but Kevin answered this question in one of the Kevin Jerk (2013 Michaluk Productions) call-out threads and Bla1ze has addressed it as well as I recall. It's not their only phone.
also there are no mobile nations apps for bb10 (they haven't bothered to make one one for our device of choice) so they kind of have to use other platforms otherwise how else will we get articles like the one a few months back on the vine app.....
I would say they use multiple platforms. You can love one more than others but that doesn't stop you from using them all. Plus with Mobile Nations, they would need to use multiple platforms in order to be able to gain experiential knowledge firsthand. I myself use all three platforms and have also used W8. I prefer BlackBerry 10.
*slowly steps away from Adam to avoid the lightning generated by the fury of forum denizens*
Love ya man, but you are so on your own...
Anyone that thinks none of us use more than one device has been sitting in the corner for way too long. We've never tried to hide the fact that we use multiple devices on a daily basis.