Why would they need or want to go public? It sounds like they already have a great product and they're profitable. Do they need to raise money for something in particular?
In a hot IPO market you generate what Adam Smith(a pseudonym) called "Supermoney" in the late 1960s.
A company which catches public's fancy can generate market values hugely over what the company would be worth in a private sale(think NFLX, think AMZN, most likely Facebook shares and so on). The liquidity and with it coming diversification is a nice plus but not the sole reason.
Of course, the company can fall from grace at some point, but even then it retains a premium over what it would be worth as a private company. This is almost by definition, otherwise the company does get taken private.