I mean, you'd still be NORDO until you fished out the cable and plugged it in. Either way, unlike the corded version, there would be a gap where you're not receiving/transmitting. (I mean, I assumed it had a cable. Not having a backup seems like it'd be silly)
Now, if you're diligent with charging the batteries, and you're not doing the kind of days that push the batteries to the limit, you shouldn't have any issues with them. In fact, I'd say if you're flying recreationally, this is probably the best combination of features in a Lightspeed.