Well the sunboard is a variation of HDPE so it's not that different. If I had to pick between the two, I would pick the sunboard primarily because of the size (other one is 14"x10"x0.375") but not the glide. I will be 100% happy with the glide of either.
They are both very effortless. I wish I had a 3310 mouse and I could test if it has tracking issues on the sunboard as well. I just tried out an Intelli 1.1 on both pads, with the slightest tilt, the mouse starts skipping on the HDPE but not on the Sunboard. If the same applies for 3310 sensors, then sunboard is the clear winner by far.
My main mouse is a G303 (sometimes G402), both of them have excellent sensors and they both work perfectly on both pads.