We were running 250 Production and 125 and 250 GP bikes. I had a Honda NSR250 friends were running Suzuki RGV250s some of the guys were running Yamaha TZ125s and TZ250s. All of these bikes were running coated bores. Prior to that we messed arround with Yamaha RD250 air coolers and water cooled LCs.
I think the first chrome bore I saw was a Kawasaki KDX 175 of about 1980 vintage. The improvement in power and reliability with the chrome bore machines was amazing. 2 strokes can easily generate piston melting exhaust temps. The exhaust port is a hole in the cylinder wall and they usually nip up or pick up the piston on the cylinder wall just below the exhaust port. Since they rely purely on the
oil in the fuel to lubricate the cylinder walls the bores get tortured in a 2 stroke.
Most strokers run pretty fat jetting from tha factory for safety but the leaner you get the more power they seem to make up to a point where something melts. water cooling and coated bores let you get closer to that limit. I've seen a few siezed cylinders and the coated cylinder wall still been servicable after a bit of a clean up. Re coating was only ever needed if the surface was gouged or the piston ring had snagged the edge of the coating on the exhaust port.
I think longevity in a 4 cycle engine running coated bores won't be a problem. some of these little 250's were making 80HP at 13K RPM
Cheers