Maybe some more information of the current Moulton models rear suspension.
There are two different design.
The AM models with 17" wheels (AM GT, AM 22, AM Speed) do not have the unified rear triangle, the bottom bracket is part of the main frame, the pivot of the rear triangle is behind it, similar to the Brompton.
The other models TSR, SST, Jubilee, Speed and New Series models have the unified rear triangle.
Even if all those models have the unified rear triangle, the actual design and behavior of the high end models Speed and NS is different.
The pivot of this triangle on the NS and Speed was recently modified because its design wasn't compatible (too wide) with the new four arms cranks first introduced by Shimano, then by Campagnolo.
Having ridden the Birdy, Moulton Speed and NS Speed, I can say that the Moulton are much more efficient than the Birdy, with the Moulton you can sprint like with a road race bike what you cannot really do with the Birdy.