I can't comment on the TuffShield, but I've abused my RaceDeck diamond for 9 months now and just made an order to replace some casualties. Some suffered from welding splatter, a few from dropped items leaving puncture wounds, but most are from hot items that were either torched off or fell after cutting.
The rest has held up impressively well, despite gritty rust being ground into them, and at times, having a layer of oil dry crunching on them while pulling transmissions. I'm downsizing the free flow tile area, because #1, it's hurts to kneel on them, and #2 rust and grit get into them and don't hose out very easily.
I'm very happy with my Racedeck, and the only gripe I have is that low lying areas that will puddle water will appear dry, but if I sit down on them, the water wicks up through the seams into my pants. If I had good slope on my floor, I'm sure that wouldn't be an issue.