I've had a QHY5. They're not real good. Very bad actually. Went to the DSi II colour and it's way way better. A friend of mine has the DSI II Pro (monochrome) and it works noticeably better again. Have a look at this
http://www.stark-labs.com/craig/arti...oundup_API.pdf
Have a quick look at page 4 - have a look at the Orion (QHY5). Yuk. So much noise.
No flexure with my system. I've got a rail on the top and bottom of the LX200 with SOLID connectors to the 127mm hanging on top and the guide camera is screwed to the back via the screwed in focal reducer. No focuser to flex here either...