To facilitate neat left-column edges in Polytonic setting, it makes sense to build-in the "hang" by giving the accented caps the same metrics as their non-accented counterparts.
However, this takes up a lot of the space preceding a capitalized word in running text.
Therefore, a contextual adjustment should be applied. But what?
1. Substitute a wider space (eg en-space character) prior to accented caps.
2. Add positive kerning between regular space and accented cap.
Some applications, of course, ignore the space character, and substitute a layout-level value. (e.g. CCI newspaper pagination system). How much of an issue is that for setting Polytonic -- can one assume that the users of Opentype Polytonic fonts will have Quark 7 and InDesign CS?