Very original ones had the original SOLO name before it was changed to 5010 (legal reasons I think?). Yeah may have been C for the original carbon but it got relabeled as CC and C was used for the cheaper stuff. All the same quality, just a difference in weight.
Love my v1 5010 CC. Hadn’t paid attention to the head angle of the v1 but later realised it’s steeper than my other bikes, yet it feels slack. Longer wheel base and cockpit I guess.
I’ve put a 2 degree angleset on my old mk2 Nomad and think that may have gone a bit too far though. I thought it was a steep angle originally but the 5010 is steeper. Now it’s super slack. Still, I like them both but very different rides. The 5010 is my favourite though. So agile and more than enough for the majority of my riding.