Albert, the Mod.2 comes with a fiber optic front sight. Grip zone is an improvement over the feel of the old xd. Trigger guard is undercut. Allows for a better grip. It has a slightly thinner profile over the older model. Slightly lighter. It's a more refined product. If cost isn't an issue, I'd say get the mod.2 if it's slightly out of your range, the xd will serve you well.

The mod 2 has some upgrades over the XDS45 fiber front sight different grip configuration including a trigger guard undercut I suggest that you handle both and chose the one that "feels" better to you