I had several colleagues that worked for Heartland, and all of them ended up leaving in less than a year. It's just the usual corporate ponzi scheme, paid 25% collections, astronomical turnover, oppressive/dictatorial management. The company tries to sell itself on its profit-sharing scheme and CE courses, but in reality many of their offices are in the red and even assuming there is a profit you (your home office) have to foot the bill for CE or anytime the management sends someone down. There are plenty of reviews online in the mould of Aspen Dental's reputation.
Incidentally, Heartland recently purchased the company I used to work for (MyDentist). An apt purchase, because the latter is just about as trashy (yes, I am looking at you, CEO Kevin Offel).