Although Rav Moshe Heinemann shlita wrote in articles posted in the Star-K website and Kashrus Kurrents publication (also posted in the Star-K website) regarding permissible shavers, he was careful to qualify that he is referring to shavers “acceptable by the Poskim who permit the use of shavers” (i.e., the Igros Moshe). Halacha l’maaseh (practically speaking), however, in a public notice on his personal letterhead dated 19 Menachem Av 5769 (which was widely publicized at the time and was posted in shuls and yeshivos in many communities), Rav Moshe Heinemann wrote that since there is a dispute between the poskim regarding the halachic status of shaving machines and those who prohibit their use consider them Osur Min HaTorah, therefore those who do not want to grow their beards should not use any regular shaver since they produce a clean shave (in contrast with a trimmer). The letter is co-signed by the Roshei Yeshiva of Beth Medrash Govoha in Lakewood (Rav Malkiel Kotler, Rav Yeruchim Olshin, Rav Dovid Tzvi Schustal and Rav Yisroel Tzvi Neuman) who add that use of regular shavers involves a sefeika d’oraysa.
Regarding the Yabia Omer (9,10), Rav Ovadia Yosef modified his position in his latter years. Rav Ovadia Yosef’s own son, the current Sephardic Chief Rabbi Rav Yitzchok Yosef (author of the popular halachah sefarim Yalkut Yosef), years after the publication of Yabia Omer volume 9, promulgated a widely disseminated kriah kedoshah (reproduced in the sefer Lo Sakifu, Holon, 5772, p. 217) quoting his father as maintaining that no Jew should use shaving machines and that one should not rely on leaving stubble (achieved by not “pressing” the shaver against the skin) and promising good shidduchim to those who grow their beards.
Many sources rejected the heter of not pressing the machine to the face, including the Chazon Ish (see recently published Chazon Ish-Shaalos U’Teshuvos section 156); Rav Shlomo Zalman Auerbach (Halichos Shlomo on tefillah, p. 11); the Minchas Yitzchok (volume 4 section 113); Rav Nissim Karelitz (Chut Shani – Inyanim page 218); Rav Moshe Sternbuch (Teshuvos V’Hanhagos 5:264). Moreover, Rav Elyashiv also categorically rejected this circumvention and ruled that if even just two hairs are cut close to the skin (which is inevitable even if one does avoid pressing), the shaver may not be used (Ashrei Ha’Ish, Y.D. p. 142).