No personal experience at all, but I have heard of them and they have a good reputation, for both rehoming and behavioural support...I might be wrong but, I think the raid was to do with living conditions rather than whether they were a genuine rescue or not.
From what I've seen online people who do know them think it was a case of too many dogs and not enough money and it got a bit out of hand rather than intentionally doing anything massively wrong.
But, like I said I have no personal experience so I wouldn't take my word on it at all.
Afaik the RSPCA thing was due to them getting overwhelmed, rather than any desperate welfare issues. Too many dogs needing their help, not enough money to do everything they needed to do and iirc, ill health on top of all that.
I think the RSPCA was working with them to try and get things back under control rather than threatening them, not least of all because the RSPCA regularly send collies to them themselves.
They are incredible people, who really know their collies and have a well deserved excellent reputation among the dog community.