My son and I have been using the SMH 10 for a couple of years. True half mile range line of sight. Hills can cut that down to nothing. Foliage can significantly cut it down also. I have the helmet speakers and use earplugs also. Plenty of volume. We only use it for intercom. We've used no other features. Battery life constantly on is 8 hours or more.
I have the Sena SMH5 which works great for my puposes. I mostly use it to stream music into my helmet. Even with earplugs in, the speakers are more than loud enough to hear at 80 mph. I've called my wife while riding (just to test the feature) and she couldn't even tell i was on the motorcycle travelling at 70mph.