Neil,
The 50kg quoted is the weight of OTA etc without the counterweights. I've got a 10" Schmidt Newt, 50mm guide scope, QSI683ws8, parallax rings and Losmandy dovetails on my EQ8. All up it would be in excess of 20kg of imaging equipment. It takes two 10kg counterweights to balance this. Here's a link to a photo of my gear before I got the EQ8.
http://www.iceinspace.com.au/forum/a...e.php?a=193547
I'm getting good guiding results with mine - RA RMS 0.8-1.0 arc seconds, peak 2.7-3.4 arc seconds. I think seeing plays quite a significant part for me as I'm in a built up inner city location.