I tried the Souber and found it absolutely rubbish for the way I do lock mortices in doors which is the door laid horizontally in a pair of choks, it probably works well for doors that are already in place and hanging vertically. It also didn’t really perform all that well on solid hardwood doors, I think it’s best suited for hollow core internal doors more than anything.
Best piece of kit for the job is a portable Ryobi DM-20 hollow chisel morticer but they’re like gold dust and very highly priced second-hand. I don’t know why they stopped making them as they were absolutely perfect for the job.
Bosch make a good corded drill, but I can’t remember the model of the top of my head.