Wayne,
Hwe it and then try and sell them a maintenance clean every few months. That way you don't have the pressure of encapping it and hoping you get it right with no experience and confidence.
We just picked up a very nice job in a prestige location that we got purely because the previous guy lm'd it even though it was extremely dirty. LM has its place, no argument there, but even if I was minded to LM certain jobs, I wouldn't do it with a new client where you don't know the history of the carpet. Alway best to get it clean first and then maintain it with LM until it needs another deep clean.
Simon