the T1 has it's dot centered in the optic just like all the other Aimpoints.
The configuration I have on this rifle gives a lower 1/3 co-witness: When brought up to a normal cheek weld the irons appear in the lower 1/3 of the field of view and are ignored while you drive using the illuminated dot in the center of your field of view. To use your irons as an emergency back up (or to verify your red dot zero): scrunch down a bit on the stock.
An absolute co-witness, by contrast,: when at normal cheek weld the irons are centered in the field of view with the illuminated dot "floating" just over your front sight post.
Either one of these co-witness can by achieved by selecting the appropriate optic / mount / spacer combination.
Which to use is a matter of personal preference.