I guess I am on the fence with the practicality point of these. I think the idea is awesome though, and can see this maybe (emphasis on maybe) changing the cell phone market for future phones. I think it's like battery packs, a few years ago how many people bought & carried battery packs? Now, they are on sale and posted here all the time. How many of us carry one now? I know I have one in my work backpack at all times, just in case. I would simply replace the Anker battery pack in my bag now with a Moto Mod battery snap-on. If I knew i was going to be somewhere and wanted to listen to music, I would snap on the JBL speaker Mod before I left the house; it doesn't look very bulky but would have to see it in person to be sure. I can see carrying all three Mods at once a bit bulky and cumbersome; carrying what you want each day (or snapping them on) may be a better way?