Is your G12C well broken in? As I already mentioned, I also felt that the G12C was a bit harsh and unforgiving before it was properly broken in. I initially thought I'd fully broken them in and had given up on them........thinking they just weren't my cup of tea. I eventually reloaded them in a cab and gave the break-in process one more shot, and that did it. I've found that the mids have become more relaxed, and the highs less harsh and much sweeter. All the frequencies seem to have settled so to speak, resulting in the G12C's clarity being the most obvious difference between the two (G12C/GA-SC64). That's not to say that they're identical, but their differences weren't night and day as they would have been had the G12C been brand new. What amp are you using it with? The amp, guitar, pickups etc, will all play a huge role in what we hear and feel. I've used the G12C with a Princeton clone, and when paired with that amp, the tone and feel of the 12C was totally different. I would have described this same speaker totally differently had I only tried it with the Princeton......like a totally different speaker. I actually preferred it with the Princeton btw. Perhaps with a Deluxe style amp, the highs would be too much of a good thing......though I haven't tried that pairing. So the fact that we're all likely using different amps will definitely lead to some differences in members' impressions/descriptions of the same speaker.