Yep, you are able to do this. It's unfortunately the only way I can play as there are no physical groups where I am. I play in 2 and run 1 game of my own. I find it much more fun than mmorpgs anymore.
As for more ontopic: I got 30 free days + SL through raptr, and tried going through the SL content using a bit of Instant Adventure, and the first zone you enter the new stuff, doesn't have the best layout in the world. Had 15 minutes to do an objective, and it took me 10 of those minutes trying to get up to the area. And like Skippy88, there seems to be a huge lack of people outside of Silverwood/Freemarch, and even in the first zone of SL. I remember enjoying Instant Adventures last year, and always having a full raid group each time, sometimes having a second group going as well. Even in Silverwood/Freemarch, I was lucky to have more than 1 5-man group. And trying to go through the SL content, I was the only one doing instant adventure at level 50, and at one point 1 person had joined me. I saw no one in the first zone doing any kind of quests or doing any gathering or anything. I also remember every zone being active, as everyone was out in the world doing something (unlike in another game where everyone had hung out in the major city of each faction). But now, if I go outside Sanctum/Meridian, or Silverwood/Freemarch (haven't been in Tempest Bay, I think it is called), I see absolutely no one, and this makes me sad. Rift was an awesome game, and seemed full of life in every zone. I honestly think going f2p or b2p would boost the population in the level 20+ zones.