When I asked Rich he told me to go with leather, and with minimal care has lasted for 25,000 miles of travel between Louisiana and Washington, not to mention local riding in a state with the highest rainfall in the USA. Besides rain I've ridden through snow, sleet and last summer, a wicked hail storm just outside Butte. My experience is that if you use Lexol leather cleaner 2 or 3 times per year and their leather conditioner at least once a year your seat will last longer than a vinyl one.
And instead of getting harder with use and weather, it will continue to soften, will be more comfortable and will not get as hot when left in the sun. I was still reluctant to go for the leather until he noted that no one would wear plastic shoes if he could afford leather, and that cattle seem to deal with rain just fine.
There is no argument that leather looks better, and Rick carries a wide variety of types and colors not available in vinyl. Given the price of Rick's custom seats, (which is worth every penny in my opinion) if you can afford one in vinyl, the price difference for leather hardly seems a deal breaker.
I was afraid to go for leather, but now I would never buy a seat that wasn't.
Opinion offered for free and well worth the price.
Ken