I think the issue of valve recession depends on the service the engine is put to. I think hard seats would be unnecessary in a passenger car or pickup application even with no-lead fuel. I have found that performance motorcycle engines suffer the valve recession fate and hard seats are a good solution.

In truck applications many if not most Chevrolet engines used valve roatators on the exhaust valves. These reduced the tendency of hot valves to temporarily weld themselves to the seat at the same point repeatedly, creating pits and eventually enough to begin leaking. Other truck engines have used sodium-filled stems along with rotators, amongst them heavy duty Ford V8s and International V8s that I have worked on. These engines run full throttle most of the time.

I had a head rebuilt using stainless valves and bronze guides but no rotators. It's run about 50k miles and is still OK but next time I pull the head for any reason, I'll install a set of NOS rotators I bought off Ebay.

1951 3800 1-ton
"Earning its keep from the get-go"
In the DITY Gallery
1962 261 (w/cam, Fenton headers, 2 carbs, MSD ign.), SM420 & Brown-Lipe 6231A 3spd aux. trans, stock axles & brakes. Owned since 1971.