Are you planning on going after really, really big dandelions? That twin tiger tooth looks just like the business end of my (manual) dandelion puller.
BOB
If you want something that will last through harder stuff (rocks, etc.) then take a look at the star style of tooth. Think of it as a beefed up single tiger.
Only real disadvantage I'd see on any other than the standard flat spade looking ones used is the cost. Both tiger, and star type teeth cost a good bit more.
What type of stuff do you plan on digging into with the FEL that you want the twin tiger teeth?
Hey! I was on the right track with the dandelion puller comment. I think the twin tiger teeth would probably work OK for shrubberies, tree seedlings, etc., though they may clog with thick turf (?). I also agree that they would likely wear faster than beefier, single teeth. Finally, if you have very rocky ground, I'm not sure how well the twin tigers would hold up.
BOB
If you desire more aggressive digging and ripping, then go for it. It is not the norm, but what the hay. If they do wear down, just put some hard surface material on them, and make them better than new.