Are All German Jews Practitioners of Torah Im Derech Eretz
No, they are not. For example, R' Binyamin Hamburger shlita of bnei brak, the renowned expert in German minhagim is not a TIDE person even though he like everybody else has enormous respect for R' Hirsch. Same goes for other researchers at the Machon Moreshes Ashkenaz. However, I have observed that one of the differences between regular Charedim that respect R' Hirsch and German Charedim that respect R' Hirsch is that the latter also are much more open to the ideas of TIDE and to its practitioners. R' Seligman Baer
Bamberger, the great German posek with whom R' Hirsch tangled on the matter of Austritt, or separation of the Orthodox from the non-Orthodox community in Frankfurt, was not a TIDE person. Lakewood posek Yaakov Forsheimmer is not a TIDE person even thought he was raised in Washington Heights in the Breuer's community. I know of numerous WH people who "went Eastern European." I don't think that R' Naftoli Friedler the one time head of the Breuer's Kollel and Rav of KAJ in Monsey was a TIDE person, nor does it seem that the current Rav of KAJ Monsey is a TIDE person, even though I know that he respects it. The same applies to the Rav of KAJ WH!
Now, most of them were not taught all that much about TIDE even in WH, even at the Yeshiva Samson Raphael Hirsch, over the last few decades. Since Breuer's types have much in common with the Charedi world, if you pluck out many of the TIDE principles you will wind up with Charedism. So isn't so much that they changed but that the schools in WH changed.
I would guess that there are as many non-yekkes who practice elements of TIDE as there are yekkes because the yekke population hasn't been all that large in centuries and the Holocaust knocked it down even further. Most yeshivish schools have a meaningful secular curriculum even in Israel at the younger grades. But is that Torah Im Derech Eretz? I argue that it is not because even much of Eastern European world engaged in some limudei chol. In my mind TIDE has other components including a sense of involvement with host societies - tikun olam and a pursuit of decorum and order. You will find some of that in the "engaged yeshivish" as Professor Alan Brill terms it but nowhere on the scale of Frankfurt TIDE.
So are there any German Jewish practitioners of TIDE? Yes. Rabbi Dr. Leo Levi, author of Shaarei Talmud Torah (translated under the title Torah Study and published by Feldheim) is a notable example. Dr. David Bechhofer, an editor of the Collected Writings, is another. I know of several other individuals from the Heights.
The role switch between WH people who went Eastern European and Eastern Europeans like me who went German is interesting. Of course, I'm not culturally Eastern European. I'm American and as I argue America is a Germanic country. That's why German Orthodoxy works so well for me and perhaps it's the same for you.