I also tried eidolon in maindeck for the fist time and won small tournament (11 players) this Thursday (record 4:0) with exactly same maindeck as you played:), beat UWR miracles (2-1), UWR delver(2-0) and 2x merfolks (2-1). Btw I keep crapy hands against merfolks in g1, but with my sb g2 and g3 is cakewalk (15 cards out and 15 cards in:)
my sideboard was:
3x bridge
3x smash to smith
4x searing blood
2x pyroblast
3x shusher

