Regarding the guitar from the RR United sessions, that F model you guys are talking about was a bolt-on neck black model with the mandatory EMG pickups. I remember seeing Robb and Jordan from Still Remains play the same guitar (the latter had a Gibson '62 SG on his interview snippet if I remember correctly).
Regarding his fabulous ESP custom V, I sadly think that it's not coming out ever, but you could order it through the Custom Shop, even though it might be over-the-top expensive, being after all a custom model. I personally think that it would be more likely for Robb not to have a signature guitar as he is playing the modified Gibson Flying V and the B.C. Rich acrylic Warlock, but hey. Whatever works for him is good as long as he keeps kicking ass! And who knows, maybe somewhere down the road he might surprise us with a signature guitar, regardless of the brand! =)