Just for fun I converted a GP se5 to a triplane this summer, it had a bit of that extra climb in it also..I am not surprised with that massive bird you needed to mechanically re trim the tail. Also I wondered when I test flew mine if the tail would have enough surface to be effective..and WOW did it need more rudder !! not only do you have to use a bunch of rudder in the turns, but I had to add a larger rudder surface just to make it fly safely..I am glad the tail was effective enough on your build, it would be much riskier finding out in the sky than my little TRIPE...
video if interested...
http://www.youtube.com/watch?v=Etttbev_ojw