You will get the Hub 4 when you sign up for Infinity anyway, so it's worth giving it a try first, and if you are happy then no need to upgrade to another router.

I've read people had issues with the Hub 3 disconnecting or needing to be rebooted. I will post my findings about the Hub 4 once I've been running it a week. So far, since the install on Wednesday it has been stable and worked perfectly, and my bandwidth is still 74Mb/s down and 16Mb/s up. And the ping rate is still 7ms which is great for online gaming.