I'm not a karate person, but wasn't too sure about the website you posted.Seemed a bit sketchy on the lineage and finer points of what they were acutally taught and are actually teaching. There was a similar post on the Judo/Ju Jutsu forum here recently, where the history behind the supposed "Ju Jitsu" being taught was rather vague to say the least!
Regarding Mr Doversola and his training, it seems hard to verify what he has said. According to the above bio, he was taught by an Okinawan Master who was a recluse. The master's name was Teiken Nagusko.
Now I googled Teiken Nagusko, and he doesn't appear anywhere else on the internet save Mr Doversola's bio.
How he met the Nagusko reads like something out of a bad martial arts film as well. I wasn't there, so it could very well be true. Stranger things have happened!
Whether or not Mr Doversola is a practioner of legit Okinawan arts, well, I can't say. The important thing is that if you enjoy what you are being taught then stick with it.
A little more Googling showed quite a few karate classes in Christchurch. That may be a little further out of your way. You could see what they do, compare it to what you study and draw your own conclusions.
As I said though, if you enjoy doing what you are doing then keep at it.