Not a bearing specialist myself, but didn't BMW changed the ball numbers inside the main FD bearing? First it was something like a 17 balls and later 19 (not sure if the numbers are correct, but the difference was 1-2 balls) because of better tolerance capability.
My mind says it's all a compromise between a high speed and huge load. For huge load more balls seem to be a better option, since there's more support area in the bearing to take that load, while it'll be limited for speed (more drag=heat and wear!). Less balls mean better speed tolerance, but probably also less load tolerance (less "support" area in between the bearing race and balls).
R11xxGS main bevel box bearing is C3 rated in stock - 'C3' means there should be increased radial clearance between the inner race and outer race, usually used for bearings that are going to run fast and hot.
So I can't see how speed can be a "problem" (R11xxGSes are rated to 200km/h speeds), I rather see the load (big bike, 2 up, lot of luggage) and potholes/harsh road conditions as a threat to the bearing longetivity.
Anyways, make sure you shim it correctly on puting it on (=correct preload) - wrong shimming will cause it broke down after just few hundred miles to few thousand, since it'll start to wear out one side of the race coz it's preloaded (by shims) wrong. If you preload it precisely right, then I've seen them lasting for 150,000+miles! So it can be kind of "lottery" between the precision of the work versus the real-life road conditions and your riding style. Some last 10K miles, others last even stunning (for the bike that has been riding offroad too, not just smooth tarmac like Goldwings etc do) 200+K miles I've heard in UKGSer forum.
Always, being a bit paranoid person muyself not to be involved into the "lottery" game - I carry a spare main bearing, main seal and few different sizes of shims with me on my travels. They're so called "GSers spare chain kit"
- but they cost less than a good chain/sprocket kit, take much less room and weight less too. I bought mine from BMW since the same
bearing from bearing shop was more expensive than from BMW.
Ride safe, Margus