In your opinion is the cost difference substantiated?
The prices I am looking at are $900-925 for the Bushmaster and RRA, and $700 for the DS, so the the price difference is about $200. I think RRA uses Continental receivers while BM & DS use LAR. The "advantages" for the more expensive rifles are chrome lined barrels (DS has unlined moly) and the RRA has a 2-stage trigger (BM & DS have single). The BM and RRA also come with hard cases and carry handles. I've got cases and don't plan to use the handle. Beyond that, it's really boils down to the quality of the three since I'm not sure the lined barrel or 2-stage trigger are necessities to me. The quality of BM and RRA are fairly well defined, but I'm not sure about DS.
For precision shooting, these days I almost need a 2-stage trigger. It is so nice to be able to adjust the creep on the second stage.