The Saint Pro is a more stable verison of the popular Saint.
"Pro" is the terminology used by Latitude 64 for the added stability, and not the plastic type.
The Saint Pro will offer considerably more fade at the end of the throw.
You can crank it into headwinds and trust that it won't turn over at all.
Lucid-X is a slightly stiffer version of Lucid plastic that tends to be slightly more overstable. A portion of the sales of Team series discs go to support that touring player.