Replacement plastic fans for convertibles have available for years. Much the same way replacement fans for early Kirbys are now only plastic. According to some sources, the plastic fans for the Hoovers were better than the originals due to the improved design of the fan. Better suction and improved air flow.
The sound is slightly different too. The original metal fans are more, "throaty", and the plastic ones are quieter. This is the same for Kirbys also.