I'd say Gossamers are along the line of 105's. We have them on our tandem. (there is a very limited selection of Tandem cranks.) Other than a tendancy to creak, like every other FSA crank I've had, thy're not bad. They don't shiuft as well as D/A.
And as for not knowing what you don't have. I currently have bikes with Dura Ace, Ultegra, FSA K Force, FSA SLK, FSA team issue, and Campagnolo cranks.