Hi
12-14kgs for a 12" F4 is very good. would you be purchasing a CF tube or fabricating?
I'm sure the EQ6 can handle well over 20kg's. especially if on a pier.
"Out of the box, the EQ6 is designed to accommodate telescope payloads up to 40lbs"
http://www.skywatcher.com/swtinc/pro...1=3&class2=302
the HEQ5 pro has a max payload of 13.5kgs but 12kg's would be ideal.
the EQ6 can handle 14kgs very comfortably. so I don't think you should restrict based on that assumption.
edit: and I don't think the 2" focuser is suited for a 12" F4. just run it by the "NEWT" online calculator
http://stellafane.org/tm/newt-web/newt-web.html
is aluminium for a spider a good thing? it could warp the ota when it cools down in the night. I know RC's use milled Aluminium spiders, but not sure if they have issues.