The CHPT3 cost 2930€, i.e. not twice and actually not that much more than a Superlight but indeed, like all he special editions its overpriced just for a special color and some different but not really better components.
Instead of making a full titanium, Brompton could do a stainless steel frame like Moulton does. These frames are lightweight and really gorgeous with all the ride benefit of steel.
And its silver brazed what Brompton should be able to do in their own factory.
Besides the frame material, Brompton should move to a real derailleur instead of their slow, dirt sensitive simple gear changing system.