I have ordered my fixed choke guns in IC/MOD over the years, finding that they seem to work very well for all around use, no matter what gauge .
However, my favourite gun is CYL/CYL.
I am not a fan of screw in chokes , I much prefer a well built gun with fixed chokes, one fairly open and the other tighter and double triggers , be it an O/U or SXS
Over dogs the choke is the last thing I worry about in a gun- if you are on the bird the thing goes down no matter what you have in the gun.
Many people feel different however.
Cat