I've been on the Vivid 150 service for some time now, and have a SuperHub 3.
After talking to a rep at Virgin today (about lowering our phone bill as it happens), he upgraded my broadband to the 350Mb/s service. All is good, it so far seems reliable and delivers good speeds.
However, the Hub 3 (which is and always has been in modem mode), now has a red light at the bottom, rather than the green it used to have. Everything works fine, no faults, the unit is certainly not over heating.