I have been playing a good bit with my kids- daughters age 13 and 10- and I have to say I really love letting their heros scrape by with victories every time. There were plenty of times I probably could have slaughtered them, but I look at it this way... if I want to play competitively I will go to the shop or have my buddies over and skirmish against them. In the campaign, the heros are meant to experience some dark, dreadful times, but ultimately they should prevail.
This, of course, means that my wonderful Imperial troops get killed every game, but I'm fine with that. Ultimately there will be 2 more Star Wars gaming fans in the world and I think that is worth some dead stormies.
I just wish I could find a way to let my younger daughter find and use the TaunTaun or Bantha she wants soo badly...