Pictures are usually limited to 32-48 bit true color in photoshop. AE allows the color display, but output into any movie container will be limited to the Container’s profile. The same goes for Premiere. It will “ALLOW” deeper color, but will only EDIT in 10bit. Dynamic link will use the XML file for the project to link to FILES and then apply EDITS from the original Program ENGINE through the use of the media cache and rendered previews. There is no drop in color until your output, and even this is done by Compression, not by the program itself. Most transitions work 16 or 32bit, but those that do not are 8 or 10 bit compatible for use with compressed video. Set your preview to i-frame only mpeg and you should get access to them after a full work area render.
If you want to be sure, make edits and basic grades in AE, but use speed-grade from premiere to grade color for output. It is designed for it, and will ensure accurate color representation in your output.
PS. Uncompressed or decompressed transcode formats for video show 24 and 48 bit color. 10 bits is usually a compression value. The color is converted and then a major value for luma\chroma is removed and only changes to it are marked in the stream. This leaves you with a 10 bit rep that is blown back up on playback. Decompressed transcodes don’t have that limitation. Premiere has a YUV 10bit previewer, but will work in 16 or 32 bits with some compatible effects. The others are 8 or 10 bit only, and work on compressed formats. This however, does not have any effect on or from dynamic link.