Grenade gloves were the worse investment I made as far as snowboarding gear goes. They run a tad smaller I think, and they're narrow. So if you wear wrist guards, forget it. I normally wear small-medium gloves, but I have a large grenade gloves and they still feel small on me. I wear wrist guards, getting them on is quite an accomplishment.
Finally, they suck in the snow. I have the "Standard Issue mittens over fingers" gloves. If you go mitten mode all day, then it works well. Nice, comfy, dry, and toasty. But if you uncap the mittens, then functionality goes to hell. The fingers of these gloves are not waterproof at all! My fingers were damn near soaked halfway into the day.
I am so disappointed, I seriously think the ghetto brand from your local gas station work better than these.