I had a chance to fondle the Mossberg today. (Had already looked the FN over very closely a while back.)
From a cursory comparison of racking the CH and dry firing it a few times, as well a detailed "look over" ... to me, the FN SLP is MUCH more refined.
Don't know how (or if) that difference will translate into much better performance in actually firing and dependability ... but the FN LOOKS to be a much better gun.