"Is ther a major difference between those bows!"
About x-50?
I would buy any Martin bow again but can't help ya on this one!
Plus, check to see if the 'X' series really is a Martin bow. I heard that they imported these to their specifications, but could be wrong. All true Martin bows are handmade at their factory.
On the other hand, if it's good enough to have the Martin name on it, it has to be good!
If I had a choice for a longbow, I would save a bit more and buy a used Vision, Viper or Savannah.