Prime Dempsey? If so, I say that Dempsey wins, perhaps by TKO. I would think that Dempsey has several advantages: weight, defense (which would be key imo), power, comparable hand speed, etc. Dempsey's too tough for Patterson.
No way in hell Dempsey had better hand speed than Patterson who may have had the fastest HW hands ever. The defense thing is puzzling as well. Dempsey was nailed with Willards uppercuts, the first telegraphed left hook Miske threw, damn near everything Brennan threw at him, several good Carpentier right hands despite them being telegraphed from miles away, he was caught coming in several times over the first five rounds against Gibbons, he was hit a lot by Firpo and couldnt get out of the way of Tunney's punches. Dempsey was no defensive genius he just gave this impression because he bobbed and weaved so much in sparring, had he actually fought like that in the ring he would have been a more complete fighter IMO but compare his sparring performances against his actual fight films and you will see a stark contrast. He often forgot defense in his rush to end things and as a result left himself open. Patterson would have opportunities against Dempsey and if Carpentier can badly wobble him I would think Patterson could do at least as well.
Yes, I believe that you're right. I was questioning it myself as I wrote it, heh. I stand corrected. But I still don't consider Patterson to be a true hw, so I take the idea that he had the fastest hw hands ever with a grain of salt. I think that honor goes to a young Ali. Imo, Dempsey's defense was unorthodox and puzzling indeed. I'm not sure what to make of it. But I think that he showed enough of it at times to make sure that Patterson wouldn't KO him like he did Johansson. His solid (though debatable) chin would help as well. Your point about Carpentier might be a very good point though.
I think the 1927 Dempsey would still have beaten Patterson . that aside, your point about Dempsey is correct .. a huge weakness for him seems to have been that when hit he saw red .. it almost cost him against Firpo for sure ..