This is huge for an extended trip. This is a must. A marriage of man and machine.
If you don't need big miles-per-day, then both bikes are on the table.
I suggest setting up the 250 and going on a trip....before this biggy trip.
Learn if this fits your groove...or not.
Sword or a knife...
The 990 might be able to out-run bad weather.
As said before (good post), the 250 will go on top of a car roof.
The 250's fuel mileage should be 50-60% better than the 990, and way less maintenance, and much longer tire life.
The 990 can carry a small butchered whale with relative ease, while the 250 would be in prison labor staus under the same load.
Try to eliminate as many of the unknowns running around in your mind as you can, before you cut the anchor line and shove off. Natural adjustments will come quickly once you're away.
Best to you on your trip.