Sounds like a mechanically efficient system to correct dento-alveolar protrusion and over extrusion of upper front teeth. System that intrudes and retracts upper jaw front teeth, maybe extrudes upper jaw back teeth...intrusion, extrusion, retraction, protraction of teeth, an ORTHO DEVICE that's more efficient than other ortho devices.
'Impaction' is when they cut a wedge of bone from the anterior maxilla...excess gum show, vertical maxillary excess. 'Intrusion' is basically when they shove LONG TEETH up into the jaw bone.
It depends. If for example, your front upper teeth are too long and too protrusive and other teeth could be moved by a combo of intrusion, extrusion, protraction and retraction as to offset unwanted; extrusion, intrusion, retraction and protraction respectively and this type of ortho ALONE would correct the hyperdivergence, than it would be a better and more efficient system than braces simply because it lets individually specific forces to be exerted on a number of different teeth, in turn giving some CCW-r to correct hyperdivergence.
So it would depend on if YOU wanted to correct hyperdivergence by this way along with a BSSO or if you wanted the type of advancement Gunson provides.
You left no link to your Gunson proposal, so I'm not going to ferret that out. Just to say that people go to Gunson when they want the type of aesthetic he gives. So, no idea if this would give same outcome or otherwise be 'equal' to a Gunson surgery. That's something your ortho would have to predict and/or explain to you.