For many years I lived blissfully without having any dealings with government contractors. Basically ASCS was, at least as far as I knew, all its work using its own employees. So it was an eye-opener in the late 80's when I started to run into government contracting, partly on the System/36 replacement project and a bit later on the Info Share project.
At least in my memory, the contractors were uniformly 8a firms, meaning their ownership was minority, women, disabled, with bigger outfits like Boeing and SAIC as their subcontractors. That seems to have continued with recent FSA projects.
Here's a govloop post from a disgruntled subcontractor (no relationship to USDA) which gives another side of the picture. Essentially the story is that the prime contractor systematically screwed the sub. Don't know whether it's true or not, don't know whether the government agency was satisfied with the performance under the contract, but it sure doesn't increase my faith in the use of contractors.