I use Linux where EurKEY is available w/o extra install. On Windows, EurKEY can be installed as a layout. I use US ANSI keycaps. The good thing about EurKEY is that ‘ä’ is on AltGr-a, ‘ö’ on AltGr-o. Much easier to remember than US International, at least for German.

I switched from ISO to ANSI a few month ago. I touch type and I need German umlauts. Just as a background. This required me to find a layout that supports umlauts. I went with EurKEY. Overall, switching was easy. I do need a larger AltGr for umlauts but overall, switching was no big deal. I do like the shape of the return key on ANSI and that there are fewer keys right to my right pinky (on the home row). Typing umlauts is slightly less convenient, especially when capitalized, but not by much. Switching between ISO and ANSI and at the same time German layout and EurKEY is easy for me. Side note: I switched for the same reason (keycaps) and for writing code.