If you dont plan to make that bucket dig into the ground much I dont see the need for it. I have used the laoders with teeth and they do make a difference if you are digging new ground. But just to scoup some stone and mulch I dont think you need one.
Roddy
You could certainly use a bolt-on toothbar. I have one on my L4310HST (which actually has a Long 4-in-1 bucket on it, but no matter). It's really helpful for digging, holding the tractor in place if you use a backhoe, raking, pulling up roots, and lifting equipment (it holds the chains in place), but you'll want to take it off to backdrag the driveway or other areas.
Jon, you will not have any problems getting one for the 4100. My dealer carries Woods tooth bars and cuts them to width for differnt loaders. You do have to drill two holes in the side of the bucket. The cost is about $375. As Mark said, great for many things but not great for back dragging.
TYM T-1104/TX10 Loader Kubota M6800SD/LA1002 Loader Kubota RTV900
I wanted to buy a tooth bar and the dealer talked me out of it.
He said to use the rippers on the box blade and then scoop the dirt and don't try to dig with the bucket (if that was what you wanted the tooth bar for).
I would have had to take it off to back drag 20 yards of compost that I was spreading this weekend.