Since the Telekom at my location provides Supervectoring 35b as the fastest offer, I have booked the corresponding MagentaHome XL.
The provisioning from a regular vectoring connection (100/40 Mbit/s) was completely trouble-free: on the announced changeover day, the Internet was gone for about 15 minutes, after which the Fritz!Box 7590 resynchronized and has since achieved a stable 265.5 Mbit/s download and 42.5 Mbit/s upload without reconnects. The net result is 249.5 Mbit/s down and 41.5 Mbit/s up.
The price of € 54.95 per month is not exactly cheap, but you get the bandwidth reliably, speed tests at different times of day document very decent data rates even via WLAN:
Unfortunately the choice of routers with profile 35b, which is a requirement for super vectoring, is quite limited. Miser. de lists 16 models with appropriate support.
Negotiated connection properties
Of course, with VDSL and supervectoring, the speeds achieved depend very much on local conditions. I am currently using a Fritz!Box 7510 (the cheapest model, which manages up to 300 Mbit/s over classic telephone lines), the negotiated connection properties show a line capacity of 314/50 Mbit/s, the maximum data rate of the DSLAM is 292 Mbit/s in the receive direction and 46.7 Mbit/s in the transmit direction.
English 
Deutsch 
Français 
Español
a report that could not have been more superficial.
not usable without actual dsl information.
Good point, have added the relevant information fresh from the Fritz!Box.