Well, my $.02 worth,

[Steve:]

the vinyl fence in Texas with our heat and sun is turning yellowish.

The cement slab fence foundation method will keep a fence lasting longer by far. Most fence rot and deter is caused by the wood touching the earth and soaking up water and later rotting. Being on the slab the wood would be suspended and kept dry, then using metal fence posts will even make things better.

Now, the earth movement will cause the curbing to crack. you can slow this down by installing rebar in the foundation of the slab and be sure to install weep holes for drainage.

Good Luck