I think you're missing the point here. It's unlikely you'll be running much single track trail on you BIG Tiger. The reasons for hand guards are several: If you fall on a BIG heavy bike like the Tiger it's possible that not only will you break a lever (and maybe whole assembly) ... but you may bend your handlebar and worst of all ... you may destroy things like the Brake master cylinder/reservoir ... or the clutch perch or a switch pod.
Plastic guards would be OK for hand protection against branches and such but when your 550 lb. PLUS bike hits the ground ... the plastic guards will just break or rotate around ... not protecting the above items.
And then ... you have your hands.
If you fall hard you want your hands protected. A Aluminum guard will take the hit and stay (more or less) in position ... you can continue to hang onto the bars as you slide down the road and your hands will be inside and protected. I've done exactly this with NO injury.
I've seen stuff broken from just the bike falling over when parked. Think about it. Big, heavy bikes hit HARD when they go down.
The good thing about the Bark Busters is that they actually FIT onto the Tiger
pretty well. The more you talk to dirt bike guys you will find out that fitting many hand protectors systems involve some custom work with a Hammer, Vise and drill. I've done all this on previous dirt bikes using mostly Acerbis products. Acerbis are good ... but it's always One Size Fits All ... which just about guarantees they will NOT fit your Tiger!
So it's more than hand protection. On a light weight enduro bike light weight plastic guards (good ones) would be OK. But, IMO, not on a heavy duty