Tell your dad to go for it. We have used twins for 4 years now. Added 8 to 10 bpa average across all our acres. We have increased our populations on dryland to 34000 and 37000 under water. We have been using a Great Plains 16 row twin. It has been a very good planter.
I see now that CIH has bought the rights to market the GP under the case name and color combo.
Kinze is coming out with a twin and Deere is selling a 12 row 36 inch twin in the south.