K’hal Adas Yeshurun of Beitar is not largely Baalei Tshuva and Geirim. I think whoever made such a rash statement should visit there, as I have.
In the KAYJ of Ramot, one may wear Tefillin in the Ezras Nashim as I have seen visitors and members doing. And the reason has more to do with the shul not having its own building, but rather it is a bomb shelter in an apartment building, hardly separate from the general community. I should know, I have visited there frequently.
I have visited Erlau on CHM twice a year and everyone davens Nusach Ashkenaz. Most of the Tefillin-wearers are descendants of the Rav and the others (and it is more than ten) told the Rav at one time, that if it is good enough for the Rav, it is good enough for them. You may imagine if you like, but I would suggest visiting instead of imagining.
There are two Yekkishe minyanim in Kiryat Sefer. One of them, run by Rabbi Goldschmidt, one cannot wear Tefillin in the main shul. In the second, run by Rav Neumann, Tefillin on CHM is the norm and it is done in the shul itself.
Rav Scheinberg was not talking about Bnei Chu”l. He was talking about residents of Jerusalem.
I seriously doubt that Rav Ulman forbade Tefillin on CHM for the Goldschmidt shul in KS when he permitted it for the Viener shul in Jerusalem. It must have been someone else.
The Tshuvos of Rav Yitzchak Karo (there are only two) are at the end of the volume. Siman 1 discusses what to do when the poskim and the chachmei kabbalah are at odds with each other. Tefillin on CHM is used as an example. See the Sefer at: http://hebrewbooks.org/1838 on page 385 (page 404 of the PDF)