Hi Alistair, I'd highly recommend the Serrurier truss, it was the best thing I ever did. It's extremely rigid and light.
Also, a wire spider is awesome as it keeps the light within the Airy disc where it belongs. I'm using 0.08mm steel wire and that's surprisingly rigid. It's much more stable than my old traditional 4 vane spider.
Regarding accuracy, you don't have to worry about that at all. As long as you can adjust the position and angle of your primary and secondary mirrors then the rest is irrelevant.
All the pics from my build are here, just in case:
http://www.pbase.com/rolfolsen/10_in...tube_newtonian
Regards,
Rolf