I own both. I'd go with the Slimblade. The Elecom HUGE doesn't quite have the right hand shape. The right side of it is too flat, and the thumb groove is too deep.
Thanks for that.. I actually bought myself a Slimblade a couple of days ago. Absolutely love it. Love the scrolling feature - very intuitive. The scrolling of the Huge was one factor against its favor in one review that I read online.
However only issues with the Kensington, on Mac OS, the back button function only works in the browsers. No where else. The other issue is that coming from a using a mouse, it is rather hard to fast and accurate with the movements, right clicking, etc. - compared with using a thumb operated ball like the Logitech M570.