I have one Sir Donnerhal gelding, Bolero NSN, shown below as a 5 year-old. He was easy to handle as a youngster and back under saddle. He is sensitive, however, soft in the contact, and not as naturally forward, although the forwardness is now good after correct training. I would say Sir Donnerhall definitely adds elasticity and to the gaits, improves the trot and canter with better self-carriage. Conformationally, Sir D’s tend to have beautiful fronts, refinement, longer necks. My guy is bold and very affectionate. I agree with others about breeding to a mare with a strong hindquarters, which is what I did. IMO, from what I have seen, Sir D’s are not as amateur-friendly as other lines, because of the sensitivity to the aids and reactiveness. But in the right hands, they are awesome!! My guess is they are slower to mature mentally, if not physically, and should not be rushed. I have not seen many Sir D’s in person, but I have studied many videos. My guy has consistently been a “Top Five” KWPN-NA horse in the keurings in the under-saddle classes. He would have been top gelding/stallion in North America at his studbook inspection as a 3 year-old had he already had his radiographs, to allow him to move into the main studbook.
http://i94.photobucket.com/albums/l98/mhaley1010/2011%20KWPN-NA%20Keuring/Bolerotr.jpg
Dreamscape Farm’s young stallion, Sir Gregory, dam-sire Don Gregory, is an excellent example of what Sir Donnerhall can throw. He also has a very good hindquarters and improved rideability, from the Don Gregory line, most likely. He is now in training with Shannon Peters.
For comparison’s sake, below is a picture of this year’s foal, Gauguin NSN, by Sir Gregory out of the same dam as my Bolero gelding:
http://i94.photobucket.com/albums/l98/mhaley1010/Gauguin%20NSN/Gauguin4mths.jpg
http://i94.photobucket.com/albums/l98/mhaley1010/Gauguin%20NSN/DSC_0059.jpg