The 1150GS plastic cases are fine (if the space is enough for you) but the F650 cases are flimsy. I wouldn't rely on them.
We lost a set in Turkey.</p>
OK, the left one was hit by a big coach which had its side door open and not much would have survived that. However, the impact, unsurprisingly, knocked the stationary bike over and the other pannier was rendered almost useless too.
Any kind of impact can spoil the rubber seal on those expandable cases and then they're open to rain and the elements.
For what its worth, the Turkish judicial and insurance system does work (slowly) and the bike now sports much better Touratech panniers.
It's hard to stay "thin" on an F650 (the 1150 can accommodate two 35
litre panniers really well) but 35 litre cases should be space enough especially
for a lone rider.</p>