Some of these chain catchers seem to be straight coming off the attaching bolt. The Sram one has a slight curve towards the frame. I just took two photos with my phone.
See how close the actual derailleur sits to the down tube
Here with the chain catcher installed you can clearly see the catcher touching the braze on to where the derailleur is attached to. If the catcher was straight at that section there would be room for adjustment.
I may have to file down the section where the Sram logo is although I wish there was a cleaner way to do this.