I have the side saddle on my M1, and yes, I do have cycling problems with light loads. The Surefire did not really give me much of a problem, but you are right that the Benellis are very sensive to added weight.
I decided to keep the sidesaddle on, because as a defensive gun, I plan to use only heavy loads. Just make sure the side saddle is not on too tight, or it will pinch the receiver. Also, make sure you try out several loads, so you know what will work and what will not work on your M1. I mainly use Win SuperX 00 for defense, and S&B 00 for the range, and I have never had a single malfunction with either of those two loads.
I also have a buttstock shell holder from Eagle (GSAC). This is a nice piece because the shell carrier is attached to the mount with velcro, so you can carry a couple of spare carriers to swap out with if you need to.
You could also use this same mount on a rifle, with the appropriate carriers.
Go with the Eagle, they make better products than BlackChicken, not to mention that all their gear is made in the USA.