Just to clear things up a bit... if you check the GS section of Andrews (
http://www.andrewscom.com.au/site-co...-guansheng.htm) you'll see the "SPECIAL Limited-Crayford version" of the GSO 12" Dobsonian, which appears to be everything in the Deluxe version (including Crayford focusser)
except the fan... hence my post.
I was just curious how much impact a fan has on the viewing experience.