When I switched in 2012 I went from 40 Mbps VDSL down, from which I got maybe 14 Mbps tops in practice to a 100 Mbps down cable connection, which I frequently hit. The shop I worked at similarly got a boost from a 40 Mbps VDSL (really 25) to a real 150 Mbps down around the same time. In 2016 I moved to my current apartment and 40/4 was still the max, while I could get 300/30 from Ziggo. Hence my 5-10x claim.

YMMV depending on the copper quality of your neighborhood and distance to the neighbourhood connection point (I don't know how to translate "wijkkast").

I have little experience with VDSL2, but in my experience xDSL delivers a lot less than the theoretical max and has a lot more variance than DOCSIS.