I don't sell them, but I've had experiences with both. I've had 4 pools, 2 with the over the wall and 2 with the thru wall skimmer. The 2 with the thru wall skimmer not only eventually had some leaking issues, which rusted the wall (one dripped down the wall for a few months from the inlet and rusted the wall until the wall cracked there) but both had winter damage from the thru wall skimmer. Another draw back from the thru wall skimmer is that its not adjustable, but many over the wall skimmers are. Over wall skimmers tend to be far cheaper too. My first and last pool had over the wall skimmers and there was never any winter damage. Although my last pool I had to cover the pre-punched skimmer holes with sheet metal and duct tape.
How do you recommend holding the hoses on the wall?