I have actually tried it, albeit only with very limited success. It is quite tricky to get one setup in a way such that it lasts. No luck at all with higher powers, but on my stock TM spring I got it going for a while, and I will say I was impressed. Now I haven't really done much in the way of comparison to the usual hop-up, as I haven't gotten it to really last. But I can say that it looks promising. I plan to try Hunterseeker's rendition of it, it looks quite promising as a solution to the longevity problem.
Spin is spin, no matter how it is applied. Except when it isn't really that simple. It can't be. While I don't think my own limited testing really holds much value, those who have gotten this thing working on ASM have documented noteworthy benefits from these "G-hops".
The way I am looking at it, even though the bucking compresses, the bb is still essentially using the bucking's contact patch as a pivot point, rotating around it as the axis, rather than the center of the bb being the axis. And it is a spin applied suddenly. A "flick" so to speak. The bb is also being forced to the bottem of the barrel, and with this flicking motion, it will certainly bounce back up. And then back down. And up. And down again, until the pressure induced by the spin buts the bb back on top and holds it there, after which it is "stabilized". But every time this bb contacts the barrel at a point other than the direct top of the barrel, off-axis spin is applied. Another idea that Hunterseeker brought up was that this sudden acceleration from the hop-up mound WHILE rotating around something other than its central axis could cause the bb to vibrate. This means an increased likelihood of unwanted contact with the barrel once "stabilized". This is all accuracy stuff. Hunterseeker's theory as to why the bb actually gets more range is also related to this vibrating idea. Think of a bb going downrange. But now, instead of just spinning, it's vibrating. Much like a top, if spun off axis, it can appear to have a larger radius than it actually does. You can look at this as providing more surface area, or the bb traveling more distance (as the extra motion means more drag). With an extended contact patch, the bb isn't being "flicked" per se, but rather spin is applied more gently across more of the bb's circumference. This accomplishes two things. It reduces the amount of initial bouncing. But perhaps more importantly for the purposes of this discussion, it makes the bb's axis of rotation at its central axis, rather a pivot around a short "bump" of contact rubber that serves as the axis instead. This would prevent, or at least reduce, the amount of vibration that could be occurring as a result of the bb rotating around something other than its own center of gravity/central axis. That is his THEORY on why extended contact patches or hop-up rubber are able to allow the bb to travel farther without actually increasing the forward or rotational velocity it has as it exits the barrel.
On a side not that would also make sense in explaining why LRBs are effective. They also keep the bb rotating on its own axis. I imagine it is something of diminishing returns, as once its spinning on its own axis, it doesn't really need the extra length anymore, which would explain why this hop-up mod could produce comparable results to LRBs.
Bear in mind that this is all theories. It could all be wrong. But at least there is experimental evidence that this is beneficial in some ways. I do intend to test it further.