I last used them a few years ago and I would rate them as the top lead vendor I ever used. Some great leads and some bogus ones but they were good with credits.
Ask to see the contract and review the refund policy. If they won't "cash" you out if you are unhappy, don't buy into. If you're unhappy with their leads, getting more leads until your account is empty seems kinda dumb.
Do they want anything to start up that isn't applied to leads? How much on deposit to start?
The mistake most agents make is we trust the salesperson who in 99.9% of the time we will never speak to again after the close. Ask to read the contract, especially the part about being unhappy and wanting to leave.
If everything looks OK to you, give em a try. If there isn't a barrier to leaving and your dollar commitment is small, give em a test run.