Like Flint, my Main Match guns for the past 12 years (Gunfighter) have been Open Tops. Mine were originally .45 Schofield, then I added .38 Spl and .44 Spl cylinders and barrels. I really like the versatility of the Open Top. While I have "all" the Open Top toys, my guns have primarily been shot as .45s, first with Schofield brass and for the past several years, Cowboy 45 Special brass. I've had no problems beyond normal wear and tear for guns shot in 4 matches per month plus a little practice.
With good maintenance and loads that are SAMMI limited or lighter, Open Tops will last a lifetime. The guns do however, benefit from careful set up as they are a little sloppy from the factory. Fix the barrel/arbor fit and fire away!!
Coffinmaker