It depends on your customer and yes, if you have warm season grasses then I wouldnt seed with a winter rye, let it go dormant. Its kinda been a joke around here with a few othe Lawn Guys, paint it. How do you think some of Pro Fields stay green in the winter. Yea its some grass, but not all of it. Tall fescue is our turf grass here. It stays green year round except in a drought. It does brown up a little in winter.
I do have a customer that mainly has Zoysia and he couldnt stand the brown in the winter. I got with my seed guy and we planted a Perennial Winter Rye. It comes out about the time the Zoysia goes away in the Fall and goes dormant about the time the Zoysia comes in. We had to add an additional Starter Fert in the winter to help. It wasnt cheap either, 50lbs for about 93.00. It is a selling point though.