I find 160mm enough for me when it comes to DH/freeride in the UK, as in the bike certainly is not the limiting factor, i am.
When i'm trail riding, on the flat bits and sometimes the up, i like to be able to attain instant acceleration to hit any obstacles i deem interesting on the way. I find 160mm bikes lack the acceleration i want and am much preferring the acceleration of a hardtail in these situations. So long rides where a lot of the time you need to make your own fun, i definitely prefer the hardtail.
I find a 160mm bike also makes trail centres pretty uninteresting.
Also which bike i prefer depends on the crowd/location im riding. If im doing is a peak bimble, and the only taxing stuff involves riding down gravel roads (people argue with this definition), the 160mm bike is wasted. If i'm going out with a different crowd, and we're making a loop out of DH tracks, then i prefer my 160mm bike.
In the alps, i would certainly say a 160 bike is more than capable of 99% of what the alps has to offer just the same is in the uk.
I guess what i'm really trying to say is a 160 bike is really a DH bike you can pedal, so needs to be used in such a way to make it interesting.