I bought my F800 almost a year ago. The odo is a few miles shy of 5k with the bulk accounted for rolling along the tarmac. It is my daily commuter year round. My friend recently bought a Tiger a few months back.
After numerous comparisons I have learned this:
-The tiger tank is bigger, but with less fuel economy we are both empty at 200 miles.
-The stock seats are near enough the same to kill your backside. An Airhawk is your friend.
-The tiger ABS is tedious to turn off.
-Aftermarket parts for the tiger are less numerous and sometimes difficult to find. The bike is still too new.
-The F800 computer controls are easier to navigate.
-They feel quite similar to sit on, however the F800 is narrower near the thighs.
-The F800 foot pegs feel higher.
-The tiger low end throttle is factory smoother. With a booster plug in the BMW they are similar.
-Both dealerships have been exceptional. Gateway BMW for me. El Dorado Cycle for him. Both in Missouri.
-The handle bars are factory higher on the tiger. Same height as the F800 with a 20mm riser.
-The tiger is more front and back balanced, where the F800 is more front heavy.
Riding and handling: There is a slight difference in "feel" (sorry for the lack of specificity but that is as best as I can do) and position. Road and off-road performance is similar, where the tiger has a slight road bias and the F800 has a slight off-road bias. I would speculate most of the differences are driver based rather than design.
Had I to do it over again, I would still buy the BMW F800GS. It was and still is my dream bike taking me where ever I want to go. My friend would still buy his Tiger for the same reason. My lack of dirt miles will be quickly remedied in the near future.
BUT... for those on the fence, In six weeks we depart for Yellowstone. 4K miles of mixed roads and dirt trails. We decided it would make a good competitive ride report.