I am using lists in my system, and for anything I have used it for, its plenty fast, and its so much more nice to work with than arrays. I have not really done over 2000 or so particles, but in a casual game do you really use much more than that at any given time? I am going to stick with lists because at the moment I don't feel that I am gaining that much using arrays and its just more of a hassle coding wise in my view.