Lets see if we can gain some foothold in this search by gaining universal acceptance of at least one point.
I contend that the quintessential murder of the killer who has come to be known by a pen name was that of Annie Chapmans. In that murder we are given lots of physical evidence, and some circumstantial evidence. Within that data are the Method of Operations and Signatures that we will need to evaluate later murders for a killer.
Are any of those attributes present in the next murder attributed to Jack? No.
Does Annies murder and dissection reveal anything about the most probable Motive?
That he posed as a client, that he subdued before cutting the throat, that he cut twice, that his next objective was the opening of the abdomen, and when the organs sought were excised, the cutting stopped.