GlobalEye is not vapourware, given how its actively in use by the UAE, being bought by Sweden and considered by many others. The Phoenix Global based platform by IMI/L3/Korea is not proven yet though, so fair on them.
Keep in mind I am not privy to the internal of the GlobalEye however, I think the main issue at hand is available space. You have an already modified civilian business jet into an AWACS platform, now you need to try and fit the piping and rig to take the refueling on top of all this. Might need some serious redesigns to the platform to make it work. The Phoenix AWACS doesn't have that issue as AAR is built in from the start.