Very interesting discussion, but thought it time to give you a little gem.
I have researched Magdalena Strohband - she was supposedly Carl Feigenbaum's sister-in-law, to whom he left his final possessions & communicated with before his execution.
Magdalena was married to a gentleman (German) named Rheiner Kosch who had a brother named Karl (with a K).
From this we can deduce it likely that Feigenbaum's real name was Karl Kosch.
I then tracked the movements of Karl Kosch, the sailor, and apart from a short stay in Portsmouth in 1884 I cannot find him anywhere near London - but, let me point out that this is far from conclusive proof.
What I did find is Karl Kosch on a ship sailing to South America in 1888, the port of call being Nicaragua.
Interesting point - Nicaragua's main fruit export was figs - German name for 'fig tree'? Feigenbaum!
From this we can probably deduce that this is when he changed his name as his next trip was to North America, and from there the trail goes cold until he is picked up as Carl Feigenbaum.
Make what you like of my research, which I did present to Mr.Marriott about a year ago after reading his book, but one thing I can assure you is that I am very thorough. Although his book is very interesting, the theory cannot be upheld when the even the identity of the suspect is in question.
No malice intended Trevor.
Feigenbaum was chosen based on a flimsy interview with a lawyer and the fact he was a seaman. If the wiki was correct (I have no reason to doubt it yet) Marriott came up with the idea it was a sailor first and then decided it was Feigenbaum. Of course that's a simplified version of it but it's basically it. There's no basis for Feigenbaum to be considered a suspect, much like alot of the suspects that have been put forth. A great hypothesis though and alot of interesting work by Marriott. Hats off to him.
In my opinion Feigenbaum is no more or less compelling than many other 'Ripper suspects'.
One impediment, for me, is the fact that we must rely heavily on what we're told by Lawton. On the other hand, we can say without question that Feigenbaum was a killer and we can point to Juliana Hoffman as an example of his misdeeds, bad character, mental instability, insanity.....pick one, or all of the above. In the end he was a murder who's life ended by electrocution. I think that counts for something and elevates Feigenbaum far above someone like Cross/Lechmere, of whom we know of no violent behavior or mental illness at all, and whose life ended after 75 years, of natural causes, in his bed.
For me, at least, another drawback is the killing of Juliana Hoffman. I don't see "Jack the Ripper". The same can be said of the crimes of Deeming, Chapman, and Bury.
In the end, Feigenbaum is interesting. It's a good theory and at the very least, a great story. That's true of Cross/Lechmere, Bury, a few others. In my view, that's about all we can hope for after all this time.
I picked up Marriott's last book on the kindle and although I don't agree with the Feighenbaum theory I will say Marriott provided some very good information and angles on subjects I hadn't seen before. I was especially impressed with his ideas about the Swanson marginalia.
It's may not be on par with other JTR books but for $6 it's worth the look.