Here's my experience with the Pelican cases as side panniers, and it's not all good, so this is a heads up to you, so you can maybe find a way to overcome this "problem".
I have a pair of well abused Pelican 1550's on my KLR. The problem that I encountered is that with repeated off road crashing, the bolts that hold the pelican cases to the mounting racks begin to enlarge the hole in the plastic of the pelican case. After repeated crashes, the bolt hole through which the securing bracket that attaches to the mounting rack is now elliptical because the securing bolt, I suppose, is stronger than the plastic of the case, so it deforms the plastic over repeated hard contacts.
I don't think anyone can ride the 1150GS in the rock climbs and technical single trails where I've ridden this bike, so it may not be a big issue, but I thought I'd mention it in case you want to somehow re-inforce the mounting holes.
As for the performance of the pelicans, they are strong, water and dust proof, but packing them requires the use of inner liner bags, or else when you open the lids, everything falls out.
Keep the good work, it looks good!