According to the handbook the rear suspension is set for an "average" rider with no pre-load. From experience I have found that 3 - 4 turns up from the bottom suits me, (13st) + BMW topbox. With a full load of topbox, panniers, tankbag and 3 weeks camping gear I turn up the pre-load to around 15 full turns. If you don't increase the pre-load you will find that you can't get the bike off the side stand as the suspension has settled right down and you need to lean the bike so far over to raise the side stand that you risk dropping it.
Don't forget you can also adjust the rear rebound damping via a screwdriver through a hole in the top chain slide and a screw adjuster at the bottom of the rear shock.
It's much easier to adjust the pre-load with the bike on the centre stand, (if you have one), as the suspension is un-loaded.
The only problem I can recall is the first time I loaded the bike to go abroad I had so much weight on the back of the bike that it was hard to steer when weaving through standing traffic as the front felt very light. I now use a tank bag + handlebar bag to put some small heavy items on the front, (tools, puncture kit, inner tube etc).
