I don't know what causes the failures, but I've seen various suggestions including the bearings just aren't up to the job, there was a faulty batch, they weren't installed correctly / over-tightened, and stress from the 4WD system. Installation issues could certainly be behind some of the replacement failures, but it's less likely to have been a problem at the factory. I don't know.

The FL2 isn't the best in its class reliability-wise, but it's far from being the worst either and is up there with the brands we tend to think of as reliable (VW, Skoda, Kia, etc), so if you are thinking of selling it I would research whatever it is you're thinking of buying as it may not in practice be any better!

I was talking to my son about this and he commented that last year he had a 14 reg courtesy FL2 with only about 1500 miles on the clock and he often felt that on pulling away that the suspension was "wound up" for a few seconds as if the Haldex was somehow initially stuck on. I asked if it could be the electric handbrake but he thought not. Has anyone any idea what version of Haldex a 14 reg would have or is that normal? 3 x FL1 2 manual + 1 auto
5 x FL2 4 manual + 1 auto
Now Discovery Sport P250 MHEV SE

The haldex is always locked when moving off from rest up to a certain speed unless the wheels are turned away from the straight ahead position and the terrain response is in normal mode. This minimises wheelspin whatever the surface. There should not be any discernible wind up unless, for example, front and rear tyres are different diameters as the haldex should release before significant windup occurs. This behaviour is normal.

I'm not sure about the haldex version in a 2014 - did the gen 5 ever make it into the FL2?

Yes, MY15 has Gen 5

I'm certain 'Gen 4' is the latest in the last of the Freelander range and 'Gen 5' for the Discovery Sport.

There's 3 variant of part number for gen 4 Haldex. I just check part number stamped on my unit and it doesn't correspond with any of these. It also has the external electronic control module.

After being able to inspect my Haldex unit in the daylight it's indeed a Gen 4 unit. I must have been given wrong part numbers as interestingly doesn't match.
This is consistent with the Evoke.
So MY15 has Gen IV.
Apparently Gen IV since MY09.
Lol, so now that's another debate as the Gen V is basically a simplified version of the IV!