I swapped the stock BMW rack for a TT one. The stock rack will certainly keep the bags off the ground and probably more, but the TT rack feels a lot sturdier, there's less flex which is good since there's plenty of flex in the main frame as it is.
Two Bings to rule them all, Two Bings to ride them,
Two Bings to bring it all and in the twisties grind them.
In the land of Bavaria, where the boxers ride...
(Gandalf the oil-stained)