I agree that the smaller dogs are better on rabbits, once the dogs get over about 32inches they have a bit of trouble getting down that low at speed.
The Deerhounds i use/breed come from an old very line, developed to be only working dogs not show dogs. (I agree that the show breeders are breeding bigger and bigger dogs that are built too heavily). The family who started breeding this line are awesome they've managed to develop the best working Deerhounds in Australia, and just recently exported two pups to Malaysia to hunt deer. (The Malaysians said that even over there they were told that