Dr Myers latest vblog post , below.
He has previously spoken about very low dose estradiol [E2] (when on Lupron) for preserving bone health. Here he is speaking of high E2 doses to suppress testosterone [T].
In essence, since male E2 is largely a result of the aromatization of T, the male body responds to elevated E2, by cutting back on T production. Rather than use a fixed E2 dose, Dr. Myers monitors T & adjusts E2 accordingly.
Myers preferentially uses E2 in older men who might do very badly on Lupron, & on men who cannot tolerate the Lupron class of drugs, but he doesn't answer the question of E2 effectiveness versus Lupron. The Phase III PATCH UK clinical trial is expected to do that, although accrual is apparently slow.
 gives some background on PATCH.