The drawback of this front mounting solution is the weight limit of 7kg (which is the total front weight, including the weight of the bag).
For the Brompton front block its 10kg what makes a difference of more than 50% in net transportable weight (such bags topically weight 1.5 to 2kg, so its 5 to 5.5kg load for the Tern solution vs. 8 to 8.5kg for the Brompton front block).