I just got the Razer Panthera from the half off sale they had, and am quite happy with it so far. So much nicer than the Mad Catz TES+. More hand room on the top surface without the bezel which can be annoying, the L3&R3 buttons are much easier to press than the overly stiff ones on the TES+, the touchpad is easy to reach, and I actually like the start button on the right side better than the front, although I still prefer it on the top. Less of a reach but still not likely to hit, and you can always lock them if it's a worry.
It feels much more like a premium product. Heavy, but not too much so, and quite solid. It doesn't feel or sound overly loud and hollow like some do. Being able to open it is super cool, even if I'm probably not going to fiddle with parts at all. I really even like the default color scheme. The true black buttons look better than the grey ones Mad Catz used. If someone was looking at either this or the TES+, I would no doubt recommend the Panthera over it.
So glad I saw that special when I did and jumped on it. I already pre-ordered an Obsidian, but this was a ridiculous deal, and so far seems like a very high quality stick. Gonna have to sell an old one or two now, but totally worth it.
My only knocks are the lack of a headphone port, no physical PC switch, and you can't store the USB cable inside without having to disconnect it, but nothing huge. I like the default art, so that's not a con for me.