I’ve never gotten gains from an extender, which is a real shame because I put together a really good rig with I think about 14 inches worth of rod extension and a vacuum cup.
The silicone shealths rip when they rub against the bars or against the lip of the vacuum cup. If you want to make them last you need to take a ring of silicone from a torn shealth and put it around the rim of the vacuum cup before putting the main silicone shealth over the rim.
Hangers are easier to use and I think safer because they have a set amount of force while the extender springs can vary wildly, change over time, and be completely depressed making the amount of force used totally unknown.
But again, I’ve never gotten gains from extenders or high weight hanging for that matter. I think using too much force on the penis is counter productive for gains.
Starting: 7"bplx5.2" 2017 (shrunk from disuse)(originally 8"bplx4.5", gained to 9"bplx6")
Current: 9.0"bplx6.125" 2020
Goal: 11.5"bplx7" 2021.