Lots of whispers in the interwebs about the 11 speeds breaking, but are they really that bad & has anyone actually broken one?
Usual - none of the happy owners tend to log onto forums to gush about them.
I used mine to ride off road from the Med to the Atlantic across the Pyrenees last month.600miles and 24,000m of climbing. Bike was fully loaded with camping gear and was very low geared. Just a couple of crunches, mainly when the groove containing the gear cable on the hub got gunged up and affected the indexing. This was the second one I've had as the first one was on the way to breaking and replaced under warranty, light and shade.
I am aware of 2 that have broken. I'm pretty sure Shimano will have it sorted by now - I wouldn't buy secondhand though. 🙂
The only problem is that they are more of an advantage to a road bike because the extra 3 gears are really on the top. (You can't gear them any lower than the 8 speed.)
There's a few threads on here discussing it. I've done about 1200 miles with no issues, loving the lack of maintenance\cleaning, it's quiet, has enough range if you gear it right and it's nice and quiet. Downside is 2lb extra weight but it feels balanced with my front end.
groove containing the gear cable on the hub got gunged up and affected the indexing
That's only issue I've had (2 or 3 times), but you recognize it after the first time and it's only been in horrendous slop where everyone else with a normaly geared setup has had to clear the crap from there mechs etc.
The first batch were bad, but long gone now. From what I've been told.