I went to a Mach at the NEC and they had one of these that was about three times the size with a double seat on, and the que to get on it was huge.
It was quite funny watching all the people go on it and watch them go upside down and all there change fall out of there pockets.
It was all cordened off so they couldnt go and retrieve their money and i guess at the end of the day there was quite a lot of money on the floor :)