At a previous company, we rotated secondary (more portable) devices around the oncall rotation. I think we used a macbook air, and some fancy portable Windows netbook. Now that iPads exist, and they're super portable, I can imagine that they'd be great for oncall. That being said, I wouldn't want my settings, say in the terminal for example, to affect mine. Although MDM is a solution, at the scale of the ~50 person company, we didn't have anything as the such, nor the capabilities, time, or money to figure it out.