I have recently upgraded to VM's "Up to 200 Mbps" service so a brief SitRep might help others.
Ordering was not straightforward as a completed form with an order number did not achieve any noticeable result.
After two attempts a long discussion with an uneducated (as in unfamiliar) eastern voice he did eventually get the new modem ordered and delivered 4 days later.
Once installed you have to dial an automated number to get new configuration data downloaded and have to wait for one hour. I later discovered that it is impossible to return to the old Superhub.
Sadly it subsequently appeared that one of my power sockets caused the new "Superhub 2" Netgear VMDG485 to fail possibly aided by the new VERY thirsty 12 V 2.5 A switched mode power supply.
By far the best part of this misadventure is that the VM engineer actually crossed the threshold in under 18 hours from the time of my conversation with the call centre who understood and agreed with me immediately. That makes a very pleasant change especially as there was no mention of charges if the fault was within my property.
The download performance is certainly faster, if a little variable, but the upload is only marginally better. Ping rates were variable too with a few delayed pings but none dropped. I have some concerns once a few more people request an upgrade. There is no change in the ongoing costs, no installation charge and only a £5 delivery charge.