Well I decided the GSO was the better of the two collimators (because it held a tighter circle when turned in the focuser), and went through the steps in Mental's thread on collimation of the GSO Collimator:
http://www.iceinspace.com.au/forum/s...ad.php?t=75601
I setup and leveled the cross-nail jig 5.5 metres from the target and found it was pretty close and needing just a little tweaking of the adjustment screws to get them all within a 10-12 mm circle grouping. So my question now is how close is close enough? I don't want to get obsessive about it and I think I am at the limits of the jig's and collimator adjustment screw capability to get it closer at that distance.
In the scope it looks great, once I get that pesky laser dot onto the mirror centre donut (using the lock screws of the focuser and abit of tape on the collimator shaft) and tweaked the primary adjusters a little to centre the return dot in the collimator window. It was close already, but I'd expect that with this relatively new scope.
Now how often does it need to be checked? I have to move the scope each time I use it (on my customised hand truck), and it's been up and down the yard many times now but was pretty darn close to perfect when I checked it.