Gerbing stands behind their products, also. I had a pair of gloves for five years, last season one stopped heating. Returned them to Gerbing and they sent a new pair of G3's.
The palm is smooth leather, same as the rest of the glove, but there are 3 gel inserts in the palm, under the leather. They make the leather protrude a bit, which helps with the grip.
I have a ganglion cyst on my wrist at the base of my thumb that I blame on the Gerbings gloves. The smooth palm means you gotta grip so hard that after a few hours of riding, it causes a painful injury - at least that's what happened to me, but I ride nearly as much in cold weather as I do in warm weather so you might get different results.
No offense, but that's not the fault of the gloves. Every pair of gloves I own has a smooth palm, and I have no issues with gripping the bars too hard (even on the Night Train with no windshield).
I'd suggest spending $10 on a Throttle Rocker, then concentrating on riding with your hands open. With the exception of applying the clutch or brake, you should be able to do anything on your bike with your hands open.