I got a cap soon after I bought my truck because I wanted to be able to have a place to secure stuff, and be able to haul stuff out of the rain. At first I thought it looked better with the cap, but after I got used to it, now I think it would look better without the cap. Maybe it's all in what you're used to seeing... That said, I do think your truck looks good with the cap, but please let us know if you want it for *use*.
If you do decide to get a cap, here are a couple of things I learned from experience. Take them for what they're worth to you.
1) The cap will NOT match your paint.
2) Get a fold-down front window in your cap. This was not an option when I purchased mine, and there is not enough space between the cap and the cab to clean my rear window! I just have to live with it dirty and all spotted up.
3) If your rear cab window is tinted and the topper has tinted windows, it will be hard to see out the back. One nice thing, though, is that you never have to flip the rear view mirror to "night" mode.
4) Get some 3M IHG to protect the cap until the paint cures. They told me not to wax mine for 60 days.
5) Shop around (if you can). The place I got my cap from beat another place by $300.
I got an ARE Z-series, by the way -- it looks like an ARE in your picture. Leer makes one that looks almost identical. I've been happy with mine so far.
Here are a couple of pics of my cap:
http://www.staff.uiuc.edu/~dneece/top1.jpg
http://www.staff.uiuc.edu/~dneece/top3.jpg
