I can't tell which one is your high poly model and which one is the low.
I'm not familiar with Maya nor Xnormal, so I'll give you some general tips for a piece like this. First, try and make the high poly mesh do as much work as it can. If you can get away with having a single face look as though there's a beveled dip in it (such as with the lip of the vase), just use a single face in the low poly. It looks like you've modeled out the lip in it's entirety which isn't necessary, a proper bake of the highpoly will yield the same results with less tris.
Smoothing the lowpoly correctly before you bake is super important. You don't want any unnecessary gradients or artifacts as those will show up in the normal map when you bake. Where there is a "hard edge" in your smoothing (this is assuming correct smoothing setup), break that UV island on that hard edge and separate the two by a few pixels. This will remove any weird black seems that you would get if you kept the island as one piece. Packing your UVs too tight is a bad thing. You need to account for mipping when you're unwrapping a mesh so that when you zoom out from the model, UV islands don't start bleeding into one another. The resolution you're baking at will determine (for the most part) how far away you want each island to be from one another. The idea is that you want the padding from the bake to fill up the gutters (empty space between UV islands). So if you bake at 2048 with a padding of 8 pixels, have your islands 16 pixels apart is a good amount to ensure the padding from each island meets in the middle of the gutter.
Take a look at these links for more info:
http://www.polycount.com/forum/showthread.php?t=80947
http://wiki.polycount.com/NormalMap?highlight=%28\bCategoryTexturing\b%29#Baking
If you make that large cut of the vase thicker (as in, pull the inner faces toward the center of the mesh), it'll be easier to bake and will read better in game. Also, that weird, extruded chunk on the right of the vase makes no sense.