I finished this earlier today and chose to let Ulysses live, and was wondering if I would have gotten anything else from his corpse, other than the stuff from that crate after you finish the dlc.

the armor and staff, as well as any items he may pick up you can loot off his body if you kill him.

Which you get in the footlocker when you beat the DLC so it makes killing him for his loot entirely pointless since he doesn't carry anything that can't be found in the footlocker.