Whether or not they're twice as good is a bit subjective, but the way they handle multiple connections is a key issue.
With the cheapo Ebay intercoms we had first, they were absolutely fine for pillion to pillion chat. Mine on its own was absolutely great for getting sat nav instructions. But connecting it to both meant long delays to reconnect when swapping between the two. Miss a few instructions on the sat nav because you're chatting soon makes it infuriating and next to useless. So a more expensive system is, arguably, a hundred times as good in those circumstances!
So I can have it connected to the bike to listen to music, it will fade out the music when intercom chirps up with some interesting nugget of information ("Oooh look, horses!") and fade out music and/or intercom to get sat nav instructions. It's also much easier to switch between different connections manually. And having an app on the phone makes set-up really easy.
But if all I wanted was to talk to pillion, I'd just get a £60 Ebay intercom.