Rat,
The roller with the pins seems to dig in and loosen the soil better where as the roller(as I'm sure you know)w/the bars seems to glaze the soil when starting out,also with the pins it seems to grab rocks and pull them out instead of riding up and over and it has a tilling effect on existing sod,it chews it up into tiny pieces and beats all the soil off of it.I'm not sure there are any drawbacks yet,the only one was the price of the new roller $1400- but you can also buy the tips individually for $8.50 ea and there are about 114 of the buggers on a 6' roller,plus you have to weld them on and thats why I went for an entirely new roller.I have some friends w/this setup and their rakes are about 3-4 years old and they still have plenty of wear left.I am also in the process of building side plates so I'll be able to carry more material without it running off the sides.If your roller needs replacing seriously consider the pins.