These bushings are fantastic for the same reasons they're mentioned in the product description:
1. Hardness. This means they'll maintain their axial hole shapes far better than softer, more porous bushings. This is especially important when using gears with very hard axles such as Siegetek. For example, I have another set in a different AEG with Siegeteks, shooting 26-27 RPS. I stopped keeping track of cycles after 1 million cycles and the F.L.T bushings have zero wear in the axial holes.
2. Flushness. These sit perfectly in line with a VFC gearbox. They offer me more room to shim, which is a huge plus given that you want to ideally start pinion-to-bevel. They also don't stick out on the sides. This means the selector plate fits above them and they aren't preventing the gearbox from fitting into receivers.
3. Smooth surface. Perhaps the most overlooked, but the smooth surface of F.L.T bushings means that gears and shims can glide without scraping or scratching. I've had this happen a couple of times on lower quality bushings and the sound is almost like a rubbing sound. That does not happen with these. F.L.T bushings are so smooth that they feel like bearings.
4. Excellent specs. I've used many sets myself and installed a good 20+ more for customers. They fit in Retro Arms, VFC, G&P, JG, CYMA, Ares, Dboys, and many other gearboxes. They also fit with the countless number of gearsets I've used them with. Should you get a little bit of a whirring noise after you shim with them, add a tiny bit of grease to axles. The sound will be gone.
Caution: The *only* concern you should have is that the diameter of the bushings is just *barely* more than advertised, which I'm assuming is intentional. If you're installing these, even for the first time, you should expect these to be a very tight fit within the bushing sockets. You may have to take a rubber mallet and really hit these into place. On the flipside, you shouldn't need to epoxy them in.
Definitely give these a shot. The price is fair and the quality is excellent.