The attached comes from the pamphlet they sent out last year when they updated all their fees and such.
Trust your math in the end, and send in what you feel comfortable not being able to sell personally if the set has a run up due to unforeseen hype.
My experience with them was neutral+. Used them during a time when I was unable to handle things for myself at the time. They do a fine job actually moving the product, but I watched many things sell at much lower prices than I would have listed them at. But they did what they said they would, move the product. After the first round of stuff sent in I looked at their current for sale price on the set before sending stuff in, as that's what they will hold the price at. Essentially you're going to lose 40-50% of the sale price to fees depending on the shipping cost. So be cautious, divide their current listing price in half, and determine if you're happy with that.
I still have a decent amount of inventory there that isn't worth the price of having returned. Mostly things I wouldn't want to look at anyways.
Keep in mind, that the ungating that happened on Amazon really affected the pricing and hold times at a place that does consignment. At the time I dumped stuff there, there were fewer sellers and if you weren't already behind the gate you had little way to get onto the platform. Their main draw now would be Walmart sales, but even that has had a huge swell of sellers. Not only are you competing with other sales vendors, but you're also competing with other people in your own consignment arena as there is no telling if your product will get picked when an item sells.