I have Navigon 8110. I am very happy with it. I really like the lane assistance feature. Maps are great and by default you get free updates for 2 years. You get free premium TMC for life (reception is a bit touch and go like any other device). Sometimes the route it chooses is not the optimum but same applies to other deioves.Navigon just released 8310 which is exactly the same hardware spec as the 8110 but with new software features.
What I understand, if you purchase 8110 you might get the 8310 upgrade for FREE. Otherwise it will cost you £70 to upgrade the 8110 software to 8310 version.Overall, I am very happy with this device. I spent almost a year looking for a satnav and settled for the Navigon 8110 and never looked back.