I ordered a set of GPM and Hot Racing C-HUbs and Steering blocks for comparison. The finish of the Hot Racing is slightly better quality. The HR is a gloss finish, whereas the GPM is more of a satin finish. The bearings pressed in a little tighter on the GPM steering blocks, than the HR(which I prefer). But the HR Steering blocks did not require shimming before putting on hexes. The GPM C-hub is a lot beefier than the HR, I was surprised. The HR C-Hub has a very thin spot that I see could be a potential weak point.
HR/GPM/Arrma C-Hubs
Here you can see the thin area on the HR I was talking about.
Stock C-Hub
HR C-Hub
GPM C-Hub
HR/GPM/Arrma C-Hubs
Here you can see the thin area on the HR I was talking about.
Stock C-Hub
HR C-Hub
GPM C-Hub