We like the round bar concaves for peas. They are more durable and with having to cut low at times the small rocks that do get pulled in do not do damage to these concaves...can't say rocks won't damage the actual rotor rub bars and tines though. In my opinion the peas are shelled by the time they reach the rotor so having more surface area to thrash with the small wire is not necessary. I know JD's cost of the round bar concaves is a chunk of change, an option is if you are a member of FNA to buy the concaves through them. As for quality they are made by a company that JD has a 25% ownership in. Seems as though JD wants a piece of the pie from those that shop around and don't drink the JD Koolaid. Good luck!