Your Wintec 500 is a decent saddle. Your trainer is just a leather snob.
I had a 25 y/o Wintec that I sold to a lesson barn. They've had the saddle 3 years now, and it's still going strong.
I have a 2000 that's at least 5 y/o and still looks brand new. Synthetics will last just as long as a leather saddle. Plus, they're easier to clean!