Way too late to the party here, but it's very good question and since you originally posted it, there's been a number of new sets and/ or new editions on the scene, such as SPII or Dave Brown's General d'Armee.
I'm still using Black Powder though, and despite its age it still gives us good games, especially if we take the time to prepare the stats and use the special rules that can really give it that Napoleonic flavour which the basic rules do not.
One of the issues I have always had with wargaming in general, and Napoleonics in particular, is the legendary search for the (likely non-existent) "Holy Grail", which leads people to drop whatever rules they may be using to take up something new and shiny that hits the market.
Nothing wrong with trying out new rules of course, and it is always good to see something fresh and new on the market. But what often seems to happen- in my experience at least- is that groups then can tend to spend more time trying to learn new rules than on being able to concentrate on game tactics. Only to have to go through the whole process again when the next Big Thing comes along. Rinse and repeat. As a gamer, I often found that really frustrating with my old group back in Vancouver.
I think it pays to stick to the system you know until you are really sure that you want to change to something else.