Well, I'm no employee of SOG, and I didn't think stating how I use my knives and the lack of problems I have had with them was considered arguing. I don't hold the lock back and fling open or closed my Vulcan or Vision. I use the thumb stud to open the blade, and my index finger to close it. If you, or anyone else chooses to fling open and closed there knives, fine. I don't do that, nor do I consider that an advantage of the arc lock design. I just don't like opening and closing my knives that way. The main advantages I see are lock strength and smooth operation.
Simply stated, the way I open and close my arc lock SOG knives does not lead to the blade hitting the back spacer. That is my personal experience which is clearly different than yours. For my purposes, these knives have functioned without any problems.
Oh, and yes, you asked if anyone had this problem, and I answered that no I don't (based on how I use my knives). I apologize if that constitutes turning this into an issue. At first I was wondering what you were talking about, because I haven't had any problems with my arc lock knives. Maybe I'm one of a few, but that doesn't change that no, I haven't had this back spacer problem. That's all.