When you have a large difference in tw, you would need to adjust the Dual Cam adjustment for the system to work correctly. The crook in the bars needs to be seated on the cam arms, and large changes in tw change this.
As for the hitch head/ bar angle adjustment, the Reese washer system offers more fine tuning over the Equal-I-Zer. In speeking w/ Equal-I-Zer on the 4 Way system, changing the hitch head angle by adding or removing a washer is equal to changing the trailer L brackets (that the bars "ride" on) up or down a hole.
The Reese SC system is very similar to the Equal-I-Zer system, but it also offers the same hitch head adjustment the DC system does. The washer and hitch head have teeth on them, and changing them 1 tooth equals aproximately 1/2 a chain link (ont he DC system) chang at the trailer bracket.
The DC can be finicky setting up as well due to the bar crook/ cam arm. I am still adjusting our DC system after a couple trips. Will find out this afternnon if it is good to go! I had asked the dealer to not mount the cam arms, but they did and one of the arms was mounted about 1/4"-3/8" back from where it should have been.
IF I was to buy again, I would look a little closer at the SC system vs the DC, even over the Equal-I-Zer based mainlly on the hitch head adjustability. IF I could (or can, haven't tried yet!), I would find a very good condition DC u-bolt system (the original model) for our trailer.
Our 1500lb Reese came with the HD chain brackets that GGardne2 mentioned.
Good luck deciding!!!