Only 30-50 flights in a Champ motor? That's a bummer. Since they're relatively cheap, I was considering setting aside some money and buying a pair for my daughters this summer, but it sounds like they might not even last to the following year. Replacement motor/gearbox combos are less than twenty bucks, but I'm not sure how simple the replacement process would be. For the cost of a couple Champs and replacement motors, I could pick up a couple radios and some electronics and just build planes with the girls.
The thing I read said 30-50 flights - I don't know how accurate it was, but I will say that the Champ isn't the sturdiest thing in the world. The tail especially is quite fragile, and it's very sensitive to wind. I spent a lot of time gluing and taping mine back together (granted, I was a fairly new pilot at the time, and I flew a lot in a small yard with lots of things to crash into).
Replacing a Champ motor and gearbox isn't complicated, but it's tricky to do without damaging the foam. The original is glued in, and you'd pretty much have to rip it out and then glue in the new one.
I've looked at a few similar planes like the Dromida Voyager, but I hear the prop shafts on those are very prone to snapping off.
There's also the HobbyZone Duet. It's not really a scale model of anything, but I've heard it flies just like the Champ, if not better, and it's slightly cheaper and definitely sturdier. It uses differential thrust instead of a rudder for steering.
I haven't done this myself so I can't offer any solid advice, but you might also check out the FliteTest foam board plane kits. They look pretty neat, and I've thought about getting one.
That said, the Champ's not a terrible plane, but it does have its flaws and limitations.