The 180mm 3.2 is a brilliant lens It has a look to it that is the closest I have been able to get to my Schneider 480mm 8x10 lens.
It is a good complement to the 250mm, but I have found that I ended up using my 300mm more when I added the 180mm to my kit.
Depth of field is very very shallow. Even stopped down a fair bit. The 180mm 5.6 is a nice lens too, but the extra 1 2/3 stops makes focusing much easier.
Here is a shot with the 180mm 3.2
Here is a Polaroid shot wide open:
I'm pretty sure this was wide open too.
As for the design type... the rear element is very large and convex leading me to believe it is of the planar type