The Hepco & Backer C Bow system offers a secure and really easy fit, lock and release mounts for their wide range of styles and capacity of panniers. As well as being secure they are visually simple and unobtrusive when the bags are off. So good that I bought a set for my new bike
When you change your bike you can keep your bags and just get new brackets.
The brackets bolt to the the 8mm thread holding the bobbins under the frame rails and allow the turn signals to stay in their original position.
On Ebay here Hepco & Becker C-Bow bag mounts for Moto Guzzi Griso 850/1100/1200 (2005-16) | eBay