While I like the middle gray surround and background of the old GetDPI, and that is indeed what I use when doing my first rendering in LR or other image processing tools, in fact my photos are nearly always exhibited/presented in museum type framing: white over-mat in a black frame. As a result, when I'm doing the finishing on rendering for printing, I switch the background color to white so that I can get the colors and density correct for that display style.
The result of this disparity is that for tricky images, I have to have two renderings: one for the museum style traditional display of MOST photo forums and another for the GetDPI-style darker exhibit environments (and borderless, since that in most cases resolves to be the same as having a darker border). In fact, one of the reasons I switched my standard JPEG output for forums to include a decently wide white border with a light drop shadow was to eliminate the need for a second JPEG display piece for darker themed websites ... The white border and drop shadow provides the eye relief required such that my standard rendering works on whichever theme for a website I put the photos up on. Now I have a completely borderless output that is intended for iPhone and iPad display, full screen, and the bordered output that goes on all web posts.
I have also found over many years that the white text on black theme (what I think of as "old terminal style") that many people seem to like really tires my eyes out, particularly at night, and that black text on off-white is much more restful, particularly in low ambient light situations.
So ... The new GetDPI theme is fine by me as is, and if a darker theme is also available I'd like to see both available as options, switchable at user discretion. And, of course, I have to say another "Thank You!" to Olaf and his team who are making all these changes and putting up with all our requests for somewhat contradictory things. It's a tough job and you folks are doing a wonderful job despite that.
G