In relation to over mounting its not just about balance.
as g-day said wind protection is a massive point but one of the biggest points is actually your mounts tuning eg backlash, meshing and the like utilizing a oag system will also push your mount further than without it.
My EQ6 is a testiment to this notion although i have got the over all weight down under 25kgs now I can run it with the 10" newt, ED 80, all cameras qhy9 mono, canon 40D, guiding and the like which is about 27kgs and still get round stars but i have adjusted and polished that white turd like you wouldn't believe!
So number one get your mount tuned and adjusted
number two, balance it well
number three, make sure its a still night
number four, enjoy your time
Brendan
