1. Avoid transparency (transparent - missing - backgrounds in vector are OK).
2. Provide a RANGE of files. You cannot possibily satisfy all needs with one file. I would suggest:
- EPS
- AI
- High resolution TIFF (will lose transparency).
If you don't want the CMYK values to change (i.e. you want the colour to CHANGE when used with different devices, rather than be mapped to stay the same), what you are doing might help, but some workflows will simply apply a default profile early on.
Crucially, prepare to be adaptable. The holy grail is one file for everyone, but people have been looking for that for a long time.