I doubt the difference (if any) will show in the first 15 days, or even a year. It’s a gamble on whether the wear-and-tear of a refurbished modle will show up in the iPad’s useful lifetime. By the same token, a new iPad can also fail. If you were to put it to numbers, it’s like getting an iPad that’s 90% or 95% unlikely to fail over it’s lifetime. (these numbers are made up).
It’s up to you to decide if the difference is worth the extra $30. The more reliable the refurbishing company, the narrower the difference should be.
It’s interesting that the company rep said that Apple was the refurbisher. I have no solid reason to doubt him, and it seems unlikely that Walmart is stupid enough to make such a claim if it isn’t true; but it is the first I’ve heard of Apple doing this, and I have to wonder why Walmart doesn’t plaster it all over the description. It’s a major selling point.