Yeah, I think it's a case of simply altered occlusion plate. I don't have the surgeon anywhere near to ask him. But this is how I understand it - along with the advancement of the lower jaw, some CW rotation must have happened. This must have been deemed as ideal, but has left me with an open bite. As there was no impaction, the plan must have been to close this with elastics, and I was instructed to wear them post-op. Now, TADs might have the opposite effect of the CW rotation, and that's why I don't know what to do now - wear the elastics and fix the bite by pulling the upper teeth down, or implement TADs. Aesthetically, they are very different options, although functionally they will both close the anterior open bite.
Also, I wouldn't say my open bite is 4mm now. I don't know, it might be around 3mm. By saying 4mm above, I meant the lower jaw should move that much up with the TADs - at least. This is because you allow for them not only to close the bite, but get the upper teeth cover a bit (1/3 or so) of the lower when the mouth is closed (normal occlusion). So, I don't know, the whole movement up may be more than 4mm for me if I choose TADs.