I'm not quite ready to close the casket lid over William Miller as there are a few more details that haven't been disclosed in this thread.
Watch Tower didn't stop their endearment to William Miller till c. 1926, the last reference to Father Miller (not simply Brother Miller). His prophecy of 1944 continued to be significant in early Watch Tower doctrine. The 30 years from then till 1974 was viewed as the antitypical period between John the Baptist and the messiah.
Len Miller (no relation to William)