Complex sentence: In spite of Klimov's concerns about decreased service life, the engine was pressed into production at the insistence of Yakovlev, and further exploitation of "PF" version showed this was the right decision.
Split into simpler sentences: In spite of Klimov's concerns about decreased service life, the engine was pressed into production at the insistence of Yakovlev. As further exploitation of "PF" version showed this was a right decision.