Grips are ALMOST purely subjective. How it FEELS to YOU is most of what's important on grips. Since no two humans have the same hands, you can only seek the advice of a fellow Witness owner with similar hands. After that, it is trial and error.
I've never heard anyone brag about accuracy of the Witness series. Not that they aren't accurate, but my experience has been they are decent, and serviceable.
Mav is correct, stock up on decent affordable ammo while you wait, then go run at least 200 rounds through it (the more the better), and check for reliability. The first thing to make certain of with a self shucker is that it self shucks and self loads with absolute reliability, and it goes BANG every time. Then work on the rest.
IF it is reliable, then look at an action tune up, and maybe a feed ramp polish to enhance accuracy. After that, buy different brands of ammo until you find something you and it like very well. And proceed to enjoy your 2nd Amendment right to the fullest.