I've also heard almost all of the DSP's on the above list and largely agree with Crion's listing
If I was to quibble, I'd probably put the D5K2 Vertical above either of the D5K5 versions, as a Centre Speaker.........there might also be a debate about the D6KVC versus the D7K2VC, even though I'd marginally come down in favour of the D6K.
Semantics though.
I'd also echo Crion's point about the Horizontal DSP's.........IMHO the only Horizontal DSP that get close to mimicking the performance of its Vertical brothers is the D7K2HC.
While the Part Numbers might be similar, the D5KHC and D5K2HC are quite a different speaker to their Vertical counterparts.
I'd also agree with George that the D5K5HC is a more pleasant speaker to listen to than the D5K5VC.
One other point to note is that the D3100HC is quite a bit bigger (18.5in to 15.3in) than the D3100VC.......which in turn makes it quite a good DSP for Centre and some Surround duties, where Space and Orientation issues are a concern........I'd try to buy 2 by D3100HCs for Surround rather than 2 by D3100VCs.