When buying any electronic product, the possibility of it failing can be worrying. Sometimes, even a new product may pass every functional test—only to fail due to a manufacturing problem once it reaches the hands of its new owner.
However, refurbished Apple products go through these high standard quality checks twice: once when they were first put into use and a second time as they get refurbished. Even if a faulty part passes the quality test the first time, it is very likely going to be caught (and fixed/replaced) during the second round of tests.
For this reason, we suspect that refurbished products are less likely to fail than new products. But since there isn’t any data on this yet, we’ll have to settle for confidently saying that refurbished Apple products aren’t more likely to fail than new products.