Specialty recruiters have greater wingspan. Their contacts work synergistically. Not only will they be able to tell you about jobs in your field, they can share news with you as well. It s up to you to determine whether your offer is competitive or not. To compete with dot-com offers, more employers are overhauling their employee compensation to include stock options and more aggressive vesting schedules.
Recruiters can describe the packages.
They can give advice. But it s your responsibility to do the research. You must be willing to take responsibility for your own search whether working with a headhunter or not.