I did my best to drink to the Sanwa Kool Aid recently, my lap times and consistency remained the same as compared to my Graupner X-8E... ironically the response rate was too fast and I had to dial back servo speed just like I have been dialing back the servo speed on my X-8E. I had bought a used M12S while I was waiting for a replacement steering drop down for my X-8E... I had every intention to make the switch but my frustrations quickly grew when it came to using Sanwa's "jog wheel", it was very clumsy and impractical to make changes to my radio settings where I was missing the color touch screen on my X-8E to quickly navigate with just a couple presses to switch model memories and make minor adjustments to my steering speed which I use after almost every race to account for tire wear.

To me the response rate is insignificant, but ease of use was far more important... I would borrow both radios you are considering and play around with a couple new model memories to see which system is easier for you to navigate and manage. I probably won't use another system without a touch screen again as my personal preference