Well, actually, I can tell you my thoughts on both.
First, the Phallosan is more of an All Day Stretcher or ADS. It doesn’t use the same traction sort of system as the X4/Size Genetics/Male Edge/etc style traction device.
The Phallosan Forte is also affixed via vacuum only. And tugs based on which leg you tie it to. Vacuum Sleeve systems can be irritating and finicky. They are not as hard on the penis as a noose style extender but they take a knack and patience I simply didn’t have. Additionally, I had issues generating good tension with it. The Phallosan is also newer technology. Take that as you wish. It was comfortable when I could get it on. But i used it to no effect last year compared to the X4 seven years ago to great effect.
The X4 Gold Edition was my first device. It got me good gains but it was a headache and a half in its own right. Nooses can be downright dangerous if poorly affixed. The system is uncomfortable, clunky and tends to detach if you move. Between the two systems the X4 has higher injury risk but what I feel is better long term gaining potential.
Also, the X4 is a Cadillac of extenders. Has two base options, extra rods, gadgets…at least my Gold Edition did. I also own the Size Genetics and the quality is slightly better. However, I’m of reasonable certainty that one corporation owns all rod style traction extenders at present, so huge differences from manufacturer to manufacturer I think are not a factor. X4 I like best personally but I’m biased.
Picking, using what I know now, I would probably pick the Phallosan because overall it is easier on the penis and not as finicky to adjust. I think if I had the Phallosan as an option it’s more attractive and user friendly than the X4 for newbie gains. Plus it is cheaper than the $515 I paid for the Gold Edition.