I did the tech spec on my 250 as well and highly recommend them. They look really good and perform very well. On the 250 they go on the black plastic panels rather than the tank itself, so they don't distract visually as you can see here:
The ones on the GSXR are the new "C3" material but I think I like the plain rubber I had for the 250 better. We'll see how well this new stuff holds up.
I've never seen the Stompgrips in person but I think they're silicone rubber. I think the plain rubber of the Tech Spec will be more durable long-term. Also, if you're considering the clear version of the Stomp Grips, word has it that it's nearly impossible to get all the air bubbles out and they'll remain visible.