Yep, the base CV64, the CV64/3d with ScanDoubler and the PicassoIV are the only cards I know of that output both the Amiga scandoubled signal and the video card signal on the same port. With the CV64/3d setup, you can even just R-Amiga-M and cycle through screens transparently. (Amiga screen flipping to a CGx screen, you'd never know the difference.) I don't know if the other two cards work the same way, as I haven't owned them.
For cards outside those three, though, you will need to use the standard Amiga video for Amiga modes, and the video card for P96/CGx modes. An external scandoubler and a monitor switch does help save sanity in those cases.
