There's been a lot of postings regarding DOF.
what i tested some years ago and found out with different still photography formats is:
1.For an equivalent field of view, the small-sensor camera has at least x-times MORE depth of field than a full-frame camera would have - when the focus distance is significantly less then the hyperfocal distance.
2.Using the same lens on a small-sensor camera and a full-frame camera, the small-sensor image has x-times LESS depth of field than the full-frame image would have (but they would be different images since the field of view would be different)
3.If you use the same lens on a small-sensor camera and a full-frame camera and crop the full-frame image to give the same view as the digital image, the depth of field is IDENTICAL.
4.If you use the same lens on a small-sensor camera and a full-frame camera, then shoot from different distances so that the view is the same, the small-sensor image will have X-times MORE DOF than the film image.
Close to the hyperfocal distance, the small-sensor camera has a much more than x-times the DOF of a full-frame camera. The hyperfocal distance of the small-sensor camera is x-times less than that of a full-frame camera.
add2) I printed both, the small format and larger format to 8"x12".
since i had to enlarge a 35mm neg. 8.46x times and the 6x9 3,38x times, the larger format yielded in (0.4X) MORE DOF.