I have the Ti Spike and it fits my melon no problem..I prefer the Ti over the rest though...Surprisingly flexible, and they don't have spring hinges...
The C5 versnio does weight a ton...especially the Light/Ti combo. It hurts my head after 3 hours or so. My Polished Black/VR28 Polarized feel lighter, but that might be all in my head.
They fit exceptionally well. I'm wearing some in my latest PW/Porno shots, check em out. I have a pretty average head size.
I had bought them, tried them on, and realized my wide head was too big for the frame, I found they pinched my head alot. Nice to look at, but not comfortable for me for daily wear.
Notice the curved outside lense(closest to earstem) on the Riddle and Spike, whereas the GC is squared. Also, the outward flow of the frame by the Spike earstem is similar the that of the Riddle. This is just all my opinions.