I've never heard of an MT-L w/spine serrations but I do have a "regular" MT with serrations. The knife is very "bad-ass" looking (my girlfriend's eyes got huge the first time she saw the thing....I was working in the yard and pulled it out, her first comment was "uh, what the hell is that thing?") I've yet to find anything the serrations cut well....they're next to worthless on wood. I do remember reading somewhere that they work well on rope though.