Although the מחבר clearly says ששים רבוא עוברים בכל יום nonetheless many פוסקים including ר’ משה felt that his intent was undoubtedly עיר שיש בה שיים רבוא as it said in Rashi. If I understood right, R; Shimon eider, and ylach”t R’ meir rosner שליט”א feel that I the road was intended to serve 600,000, even if not necessarily at the same time or even day it constitutes a רשות הרבים דאורייתא. I think that they have always expressed concerning London that even if one makes various strings and צורות הפתח one is nevertheless transgressing an איסור דאורייתא and is חייב כרת. Rabbi rosner also withdrew his local eiruv from the shefa Chayim when it opened to public traffic.
I assume the mekilim – including מרן הגאון ר’ חנוך ארנטרוי, אב”ד לונדון feel that the mechaber should be understood literally, and with a good eiruv one may carry. [Rabbi ehren trau is מחמיר for himself, but he has expressed numerous times the כשרות of the eiruv.]
I am unaware – due to pure עם הארצות – of the various קולות concerning more than ten אמות, however they were originally quite מקיל, later they fised it up. I thought it had something to do with ראשנים who hold that a צורת הפתח works on more than ten amos, unlike the רמב”ם and מחבר.
According to common belief Rabbi Ehrentrau is a tremendous boki in eiruvin, and is familiar with all the דברי החזון איש, alongside his vast בקיאות in many other סוגיות. nonetheless the majority of local רבנים have expressed the opinion that the ערוב is a ספק דאורייתא, so they obviously feel that even with whatever has been established it still remains a רשות הרבים דאורייתא