Specialty would be the way to go, but if you are in cooler climate or want to able to bale straw more easily a standard rotor would be fine. IMO
As for price on s/h machines with standard v spec. it would be very minimal. You may get a slightly higher price for a spec.
I had a 1666 with standard rotor and I loved it. Didn't really want to trade it, but went with an 2005 2388. Anyway I put an acceller frontend on it, made new machine out of it. I would run it against any specialty rotor. I have corn and soybeans, no more romping in green beans.