Hello,
I wanted to help you with a few of the questions you had about corporate recruiters.
How to compare recruiters? First off make sure that the recruiter you are dealing with is with proven company and already has relationships with the companies that you may be interested in joining. This should speed up the interview process and cut down the middle men.
What are some of the cons of using recruiters? The only cons would be if you are using a recruiter who is charging ridiculous fees and you are having to pay him or he is charging the company fees for things like taking you perm if you are on contract. Most larger recruiting firms already have contracts with companiesand set rates and they are happy to see a good candidate from the recruiting firm they have hired to fill the openings.
Is it advisable to work with multiple recruiters? Working with more than one recruiter will open you up to more oppurtunites with different companies. This is because most recruiting firms have contracts to be preferred venders for paticular companies. This biggest thing is to make sure you know all the details about every position in which the recruiter appplies you for.