given DLM, the nature of VDSL to vary in its performance, I think its wise to keep a seperate modem/router, even tho as kitz pointed out it is extra cables.
If I had a line that was 80/20 with spare snrm I would be less wary, but I dont so I will defenitly keep using the hg612.
There is also future spec changes to think about such as vectoring, will 3rd party router/modem combos work properly? only time will tell.
The extra power cable doesnt annoy me much, but I admit its annoying a gigabit port on my ac66u is wasted on collecting the hg612 stats. Because of this I have a desktop machine connected to my lan via a BT AC wireless dongle.