If you ended up with all of your acreage in a 1280 unit, that would probably be better provided it actually gets 6 wells drilled. If a 640 unit allows for 3 wells and all your acreage is in that unit, then there are fewer wells than in the 1280 unit. I personally think it would be better to share in 6 wells than 3 wells, though your royalty interest in the 640 unit would probably be twice the amount in the 1280 unit. All of it depends on how good the wells are in each unit. If the wells in the 640 unit are poor, better to have your acreage in the 1280 unit. If the wells in the 640 unit are big wells, you might want that. But, you really can't know in advance how good the wells are going to be. That's the rub. I'd go with the 1280 myself thinking that the average might be better in the long run than 3 wells in a 640.