No experience with the Gossamer crank, but I had an older FSA SL-K carbon crankset on my bike... which quickly loosened and fell off. The interface between the through axle and the left crankarm became so worn that no amount of tightening on the fixing bolt could keep them together.

Not really happy with that. Out of warranty, so no recourse there. Ended up getting lucky and buying some cheaper ultegra cranks.