Tron's shaker integration is good, but not overused. It comes up pretty infrequently early on
when you are playing but as you progress further into the game it is more evident.
I've only played an Iron Man with a shaker very briefly and the shaker seems to be used a lot more
in that game.
I had the same dilemma when I got my shaker, I had a hard time deciding whether to put it in
Spiderman or Tron. I got lazy when I realized that my Tron was already t-nutted for the shaker
and Spiderman was not. I put it in Tron and have been happy with it.