Opinions on risers and extenders?

Ok so, I have yet to use any kind of risers in my newly built rig, I just have my 2 gpus plugged directly into the mobo bc I have 3 pcie x16 slots (one 4.0 and two 3.0s, kinda got stuck with it bc of the newegg shuffle combo and didnt wanna lose any money by reselling lol). But I am going to buy them, just wanted to see how the heat would be being directly on mobo for the last week. Obviously the most popular for us are the pcie x1 risers for m2. BUT I came across full size x16 extenders that I didnt know even existed. They are just x16 to x16 extenders, and I'm wondering if this would affect hashrate to keep it maxed out without alot of overclock or have any other benefits vs the risers everyone uses Has anyone used these? I want to try them out and see how they work. I think they would work good the way I have my rig built at the moment.

Opinions? Experience with them? Please let me know what you think.