Big companies don't avoid GPL because it's "untested". Big companies avoid GPL because it's actually quite dangerous for them to use. GPLv2 only so far as if they accidentally taint their proprietary code with it, then they need to open up their code (which is bad enough). But GPLv3 is really fucking scary. As it was once put to me, if a single GPLv3 binary accidentally makes it onto the OS image for iOS, Apple would then legally be required to release the master signing key to the whole world, completely destroying the whole security model of iOS and screwing everybody (not just Apple but also Apple's users who rely on that security). Plus the patent clause in GPLv3 is also nasty.