Hi Mario,
Hopefully I can give you at least an insight to the ED120, especially with regards that we are both using a QHY8L. I have had mine now for around 3 years and I absolutely love the scope. I have added a Moonlite focuser (with DC motor option) to it. For imaging, you really do need a flattener and I use both the Hotech SCA Flattener or the latest revised William Optics 0.8x Reducer/Flattener III such that I can "speed" up the rig from f7.5 to f6.
Here are a couple of recent examples of images. The first set from a dark sky location and the second from metroploitan Adelaide.
http://www.iceinspace.com.au/forum/s...ad.php?t=88312
http://www.iceinspace.com.au/forum/s...ad.php?t=94019
For a while now I have been seriously contemplating purchasing the new Skywatcher Black Diamond f4 imaging newt to replace the ED120. The only reason behind this is to image at F4 (at a similar focal length), which would mean 3.5x quicker imaging over the native f7.5 of the ED120. But, I am very unsure to how much more "work" would be involved in using a very fast newt over the ED120. I hear a lot about critical collimation and continual collimation tweaking, mirror flop etc with a lot of these f4 newts.
From an ED120 perspective, every time I image, I am truly amazed to how truly "plug and play" a refractor is. I recheck focus about once every hour and that is it!
So not sure if I have helped in any way, but please do not hesitate to send me a PM if you would like any additional info etc.
All the best!
Daniel