I've used in-channel and stick on. The problem I've had with in channel visors is they put additional pressure on the motor and could hear the motor working extra hard as it reached the top. Long term use can also deform the window seals. I'm a big fan of the stick ons. . The windows are huge on the Forester so it's unlikely the visors are big enough to block sun from hitting you from the side. I'm going to put black vinyl on the top 6 inches of my drivers window to stop the side glare. I highly recommend Vet Visors for your Forester, I've yet to have a set that increased wind noise and they keep the interior air fresh.