It's a travel agency based on the points business. I have never heard of anybody screwed over by him. I've done numerous transactions with prompt payment. As in same day. Not some fly-by-night.
One second - is this guy selling tickets booked with miles? Or is he signing up for credit cards on your behalf and giving you a little cash? This thread is about the latter.
Big and established is worthless. Guy across the hall from my office had 60 employees in 2012 and had been open for a few years, selling refis to little old ladies. Apparently he wasn't actually refinancing, and a team from Washington closed him down in under 5 minutes after they walked in the door. Just like in the movies.