I don't think the Gagne deal is a bad one. I just question whether or not you could've gotten more (or more later).
I'm in a similar league -- set up based on your recommendations somewhere on this site -- and I think Gagne would've gotten more in return. He's going to be a top 12 skater for most competitive teams in your league (even if he does miss a handful of games due to injury). I can't help but think you could've gotten either a better prospect or a better pick.
You had the depth to afford this deal. I just wonder if someone with less depth would've given more to get him. I'm not sure you maximized your strength enough.
Always easier to say when not doing the one dealing though. Maybe I'm off-base. I hope it works well for you!
Points-only, Full Keeper Dynasty League
Active roster (no starts, just total points): 12 FW, 6 D, 1 Goalie
Forwards: Ovechkin, D. Sedin, Stastny, Nash, Kesler, Ribeiro, B. Richards, Selanne, Hossa, Fleischmann, Whitney, Lecavalier, Alfredsson, Okposo, Plekanec, Doan, S. Kostitsyn
Defense: Goligoski, Campbell, Gonchar, Bergeron, Liles, McBain, Vatanen, Timonen, Visnovsky, Giordano, Wideman
Goal: Luongo, Holtby