Q. For those of us that follow the custom cited in the Ramo to wear weekday clothing on Shabbos Chazon, a custom that was practiced throughout the Rhineland for generations, is it OK for us to circulate among others of our Jewish brethren that practice Shabbos Chazon attire differently?
[There is an observation (Leket Sichas Mussar, Vol. 2, pp. 266-267) made by Rav Yitzchak Aizik Scher zt"l, Rosh Yeshiva of Slabodka, that our ancestors who wore weekday clothing on Shabbos Chazon did not do so because their feelings for the honour of Shabbos were less than our own. Rather, our feelings for the Churban Beis HaMikdash are less than theirs. Hence, we rely on the view of the Vilna Gaon and wear Shabbos attire on Shabbos Chazon, contrary to the customs of our ancestors.]
A. In our times it is not difficult to find a minyan in which people who are in the process of kiruv attend, and they often wear clothing that may not qualify as your regular bigdei Shabbos.
Horav Moshe M. Lowy Shlit'a commented in the name of the Chasam Sofer, that wearing weekday clothing on Shabbos Chazon in times gone by, was not considered a detriment or an impairment to the kedusha of Shabbos. On the contrary the deep feeling of the loss of the Beis Hamikdosh, imparted at the same time a profound sentiment of joy and simcha, since that feeling is an assurance and guarantees that the geula will soon come and the Beis Hamikdosh will be rebuilt. That profound notion may not be so common in our days, and therefore most avoid weekday clothes on Shabbos Chazon.
Horav Shlomo Miller's Shlit'a opinion is that there should not be great concern in being dressed differently than others on Shabbos Chazon, when keeping up with the minhag of wearing weekday clothing, since one may comply by just using a weekday tie or similar.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit'a