I agree Proac decided on a very poor nomenclature to distinguish among the D30 line. It's confusing especially when folks tend to add an 's' to the speaker designation when talking about a pair. First off, an 'R' in the name will mean a ribbon tweeter and a second 'D' in the name means a dome tweeter. The 'S' designation at the end of the names refers to the newest version with updated drivers and x-overs. From Proac's website "ProAc have updated the D30 to a D30S. Still available in a dome or ribbon tweeter - Response D30DS and D30RS respectively". Best to look directly at Proac's site when considering any particular speaker in the D30 line then look at the specs. Better yet, have a listen to the particular model you're interested in .
I had the D20R home and was impressed with the ribbon tweeter for its balance, resolution and horizontal axis of dispersion. My question is whether the D20 line is next up for an 'S' version update?