Didn't use a licensing service, but it sounds like a waste of time and money to me with the possible exception of one of the more difficult states to get a license in (like Texas, Cali or Florida). I could see that if you had a service that specialized in a difficult state, they might help you avoid some pitfalls and possibly even save some money. Probably not though and you are still going to have to do the hard parts, requesting diplomas etc, anyway.
I would advise you to stay way the hell away from FCVS unless your state specifically requires it. Theoretically it is a great idea. In reality, the state that I applied to that accepted FCVS had their own application packet as well. There was no separate application packet for those applying through FCVS and those applying without FCVS accounts. There was no money saving because you still had to pay the same full fee as non-FCVS applicants. Perhaps there is a state that will accelerate your application if they receive your info from FCVS and that could be a reason to go with them, but I doubt it.
If you tell us which states you are/ might be applying to, we might have better advice.
- pod