If no one has any experience on them here - and you don't find anything about them - my advice would be to go along and look at the car and chat to the people there - go when you have plenty of time and be in no rush.
I managed to find little detail, good or bad, about the independent dealer I bought my car from last year, but once I'd spent time there, spoke to more than one person and generally took in the atmosphere of the place and how they dealt with other people - I built up a very positive picture in my mind.
I actually spent a fair bit of time there in the end and was able to get the car driven to an independent specialist for inspection, and able to write down all the details about the car and history to check it out later.