I'd prefer a ST4000XCM.. sure its only 4mp, but its QE is higher, My scope wont cause extreme vignetting with it and its nowhere near 21k...
Sensitivity is pretty important.. for me, anything that peaks around the 50% mark is acceptable... I'd love a STL11000XCM, however at 32~33% QE in Ha it would be a camera that would require you to do megadata images to get good detail...
I must say, I like OSC imaging... Sure you lose some resolution, but its just easy... Easy - Easy - Easy, and im Lazy - Lazy - Lazy..