I have both the 160 and the 180. I cannot say bad things about the 160. Pics are as good as any other Hassy lens.
It is smaller and lighter than the 180, as you can see on the picture below.
I think the main reasons for buying one would be,
1) you like the field of view better than the 180mm (although the difference is minimal),
2) you find one at a price which is too good to pass (which is the reason I bought mine, and therefore I use it from time to time.)
3) you want something smaller/lighter than the 180 (but then, look more toward a Tele-Rollei or small format?)
To comment on your point "we don't hear much about this lens": true, its production was much shorter than the other two. The 150 was introduced at the beginning of the system (late 50's) in C version, the 180 sometimes in the 1980's during the "CF era", and the 160 much later (2000's maybe?).
If you already have a 150, you're probably not gaining much from the 160 - except for reason #2 above

The 180 is much more different than the 150, if you don't have infinite funds I suggest saving the money toward a 180 instead. You'll open more possibilities.
(But on a side note, if you look at my previous posts, there's one recurring line of mine: you'll end up having all Hassy lenses eventually anyway

)
Hope this helps!