So I've had mine for a few weeks. Here's my thoughts on it vs the CST Lasertrak (1600dpi, scroll wheel, no additional ports for extra buttons). Now, I got the Slimblade, because I need more mouse buttons. I also game and Photoshop on my Slimblade. My CST I just use for day to day computer use, with a little bit of Photoshop here and there.
2545 vs Slimblade
I never though I'd say this, but I prefer the scroll cylinder on the CST. The biggest factor behind this is, unless you're a robot it is almost impossible to scroll with the slimblade without accidentally moving the cursor. I really like the scrolling mechanism on the Slimblade, but the fact that I subtly move the cursor when I scroll is what bothers me the most.
The additional buttons on the Slimblade are nice, but I'm still getting used to them. It definitely didn't feel as natural as the CST. But then again the Slimblade has 4 buttons. Now let me just say that there is no comfortable place to put your hand that makes all four mouse buttons on the Slimblade easily accessible. I mapped my Mouse 1 to the bottom left button, and Mouse 2 to the top right. Mouse 4 is top left and Mouse 5 is top right. I've been using the Slimblade exclusively to play World of Warcraft, and having mouse 4/5 bound makes it somewhat of a pain to use. I've since gotten used to using my Slimblade slightly differently than my CST. My fingers rest further down the mouse, and my ring fingertip sits right at the bottom right corner of the top right button. This allows me quickly to go from the top right button to the bottom right button with little movement. Hitting the top left button, and the "Mouse 3" which is combination of Top left and Top right still requires me to move my hand. This is a huge dislike. It feels like I really only have 2-3 mouse buttons, and doesn't feel nearly as natural as a normal 5 button mouse.
The CST's ergonomics aren't horrible, but I would suggest a wrist rest if you easily get pain in your wrist. Using it for hours at a time, I don't notice any stiffness, but then again, I've never had joint problems. I could see this being a big problem with people with sensitive wrists. You aren't putting any pressure on your wrist itself, but it is angled where it makes naturally mousing around, crook your wrist at a strange angle.
Build quality seems to be the same for me. Obviously the wear and tear will show with more use, but so far so good. The Slimblade has ruby balls, which I'm hoping won't wear flat like my MTO. The CST require a little lubing with teflon silicone before it became smooth. The scroll wheel on the CST also required a little pushing and moving to get it to feel smoother. Taking the CST apart is much easier, and makes more sense than the Slimblade. The CST also has a standard ball size, so you can interchangeably swap them out with pool balls. Neato!
Overall, I don't really mind either one. I still prefer my thumb operated trackball, but that's because I've used it for almost a decade. I wish CST sold individual switches that I could add to the modular 2545, instead of having to build my own out of legos and cherry mx switches (ripster). Other than the odd button placement, the somewhat stiffer mouse buttons, and the scrolling mechanism moving the cursor around slightly, I think the Slimblade is a great candidate, and definitely worth the money if you're getting one for $70-$80.