Looks interesting and quite simple while maintaining adjustibility. The only concern I might have would be the lateral stability. The model in the first pic looks to have quite a narrow base, however, the one on the left of the pic with three (has the G27) looks to have a wider base to accomodate the pedals.
Well they are definitely different in one way. Look at the unit on the left, look at its support bar. Its swapped from the two on the right. Totally different. It may indeed be wider.
According to their website, the bases are in fact all 12" wide. I don't know that 12" would provide the stability necessary.
Link: http://steeringwheelstand.co.uk/earl-range