Yes, but I got a 'second hand' cancellation so didn't pay the full amount.
They have a range of bikes not just the 1200, many people choose the smaller ones maybe G650GS or F800GS now, bikes have changed since I went. You will get put into a group based on perceived ability after early exercises, so people don't tend to get left behind or bored depending on level.
It was good and they teach you a lot of bike handling skills applicable to different terrain rather than just how to get around an enduro course like some of the cheaper options.
Although there are other options based on this type of school possibly down your way more such as
http://www.adventureridingacademy.com/
That is run by Patsy Quick who used to teach at BMW Offroad.
Another option is to go down on a long-weekend to Spain and get some tuition from one of the companies there. Doesn't work out a lot more for guaranteed sun.
I guess it depends on what you want to do. If you want to be able to ride enduro maybe or the UK rallies or greenlane better the enduro type schools might be best. If it is overall non-paved road skills then the BMW or one I linked above possibly better. Although both translate to some extent I suppose.
For me though it was a case or rubbish in, rubbish out. In other words I was rubbish before and after
But at least I knew what I should be aspiring to do.
I did an off-road tour in N. Thailand a few years ago. It was fun but nothing was as tricky as some of the bits on the offroad school course. So from that point of view it probably would have helped.