Some info on the GSO 8in. /F4 below - there is a link to a comparison with the Vixen RS200.
I have had 2x GSO 8 in. F/4. Newts. Good quality for the price - only did basic AP so can't really comment otherwise. Collimation had to be exact as expected. Vixen quality is a step up.
http://www.cloudynights.com/item.php?item_id=1677
http://www.cloudynights.com/item.php?item_id=648