Before I used 2 inch diagonal with SC thread. I found it a bit tricky to switch eyepieces all the time, in particular in the cold. It was also tricky and annoying to rotate the diagonal when using a German Equatorial Mount. So I heard from people that the Baader click-lock diagonal was so great and that switching eyepieces was quick and smooth. So I decided to buy it to test it. The result were impressive. This diagonal is VERY good and I really love the click-lock mechanism. Switching eyepieces is much easier now, and faster. The quality is top notch. This 2 inch diagonal is also a bit smaller than my previous one, which is a plus.
I use this diagonal with EdgeHD 800 and I also had to buy the Baader 2'' ClickLock SC clamp. This combo works great, and it is very easy to rotate the diagonal now using a German Equatorial Mount and to switch eyepieces. The only downside is the total cost. The Clicklock SC clamp is a bit expensive, and you need an adapter if you want to use 1.25 inch eyepieces, which is also expensive. So you have to pay a bit for the SC clamp, the diagonal and 2 inch to 1.25 inch adapter.
Conclusion: I highly recommend this diagonal, despite the cost. :-)