I think it would depend on which bag you have clipped on. Obviously (if you've seen pictures of them) if you don't have a tank bag clipped on the fuel cap is out in the open.How does the bagster affect fueling up?
Doesn't slow me down. in the front you have two locking rings, I leave the right one unlocked and just unsnap the rear and swing it out of the way hanging from the left front clip.
I don't have mine for the FJR yet, (still waiting my 3 weeks delivery time) but as mentioned earlier, I have one already on my Aprilia. On that one, with the smallish bag I have on it, I can just release the two rear quick disconnect clips (squeeze to release) and the tank bag hinges up and forward enough to fill. I imagine it will be even easier on the FJR with that bag since there is no cross-bar on the handlebars like on the Pegaso, so it should flip even further forward.