Some MSC's only use scheduling companies, so it's a non-question for them. When I've seen shops listed by such a company, I'll cross check them with the company's ad. I've found that they match nearly all the time. I've seen bonuses a couple of times offered on the MSC's site that are not on the scheduling company's site. I've seen it the other way around once.... When I can, I prefer to go through the MSC directly. I find it easier to ask for a bonus and I'm more likely to be able to self-assign...
Hard work builds character and homework is good for your soul.