I'm trying to counteract what I consider a naive assumption that internal recruiters are more aligned with your interests or the firm's interests than are external recruiters. In a startup, yes, you are more likely to be talking with HMs directly, in which case they probably don't have access to the rigid job tables and classifications that professional recruiters use. They are also more able to tailor a job req for a specific candidate so they don't have to stick to a rigid salary range. At the same time, they also probably have limited budget to work with, so your ability to negotiate will eventually hit a wall because they simply can't afford to pay that much.

In medium and large companies, I think that recruiting is largely a revolving door. They work on contract, they are in it for themselves, and their primary motivation is to close deals fast and pay you the bare minimum they can to close the deal.

I merely wish to warn that you shouldn't distinguish internal from external recruiters. The main point being that in this negotiation, you can't trust anyone but yourself. Focus on impressing the hell out of whomever makes the decision, then you can bargain for a better deal.