The difference in ride between a Tern and a Brompton is chalk and cheese.
In my experience of owning both a Tern (D9) and a Brompton, the Tern wins hands down. They feel much more like a bigger bike, they roll better, are quicker and are more comfortable. They also look less like a clown bike
Where the Brompton does win though is the fold, but that's all
All my own humble opinion of course.
A Tern with hub gears and belt drive would be a fantastic purchase.
In my experience of owning both a Tern (D9) and a Brompton, the Tern wins hands down. They feel much more like a bigger bike, they roll better, are quicker and are more comfortable. They also look less like a clown bike

Where the Brompton does win though is the fold, but that's all
All my own humble opinion of course.
A Tern with hub gears and belt drive would be a fantastic purchase.