They do prevent a whole lot of fine debris, especially tree flower bits (bracts) and dog hair, from getting into the filter and I save much water by not having to vacuum to waste or backwash. The pump pressure doesn't appear to be affected, the gauge stays steady.

Yes, the socks do take a beating but they really are very inexpensive in the overall scheme of things. I go through maybe six skimmer socks in a season. My pool store sells 5 for $6 and they sell for less than that on eBay.