I like the Green for Kesler deal for the exact reasons you listed. There's significant risk for both parties but also the possibility for significant rewards for both as well.
If I was a Letang owner, I dont think I would deal him for Kesler myself, so I can appreciate your apprehension to make that deal.
As far as O'Reilly, I am not sure why you dont see his upside. That kid is the real deal.
10 Team, Points Only, $$ League, Keep 20/25 at seasons end
25 Man Roster, top 20 monthly point getters count
Goalie points W=2pt L=-1pt SHO=2pt
Stamkos, Tavares, Hall, Couture, Hanzal, Wheeler, Stastny, Versteeg, Fisher, Hornqvist, Eriksson, Hodgson, Setoguchi, Turris, Steen, Letang, DRoy, Yakupov, Grabner, Byfuglien, Baertschi
G-Rask, Halak, Schneider