While I own one, I haven't used it ...yet, so this is an interesting pro and con debate. While it may be best to plane all the work to a uniform thickness, I wonder if jointing one face, opposite/alternate, would give a registration surface? As long as the surfaced face was down on the table would it matter if the opposite face was not surfaced?
This way all the rough surfaces would be ^ up? Just throwing that out for "debate"
Important to again note, than no-one I know in North America uses a joint bit, even although these things have been around forever. If you try one and you don't have patience, I will be surprized to not see it ending up in the trash can.
This is what I did on the top pictured in the thread.
I glued up in the rough, without planing any of the faces, because I wanted the top as thick as possible and my boards were reasonably equal thickness. Also the Maple I am using has a lot of cross grain in it and although I know how to grind blade angles to give no tear-out for this scenario of face jointing, I could not afford the time. Both edges were jointed, I could of used the joint bit to do this also, but the fence on my shaper was not long enough and I did not want to waste time making a fence for the job.
First board, measure thickness in several spots with a vernier caliper and obtain the average thickness. ( I can measure up to 0.001")
Measure the thickness of the joint bit.
Subtract the width measurement of the board from the width measurement of the joint bit and divide by 2.
Set the board on the shaper, lying right next to the installed joint bit. Set the vernier caliper to the dimension calculated above, one end on the cutter and start adjusting cutter height until the caliper depth point touches the board. The inner cutting edge should miss the jointed edge by about 0.001 by adjusting the fence, so we maintain the jointed edge.
After milling the first board the next is milled with the top facing down. If the next board is thicker or thinner than the previous, we have the choice of setting the cutter height to exactly match on one side of the table top, being an equal top face, or we have the choice to set the cutter height to divide the difference, meaning there will be a slight step both top and bottom of the table top.
I ended up within around 1/32" on my glue-up offset both faces. I could have aligned perfectly on the top of the table surface, but there are rough sawn marks that are also aroud 1/32", which is why I did not bother, as these have to be planed out.
Long time ago, 8 years I drove past a chopped down Walnut orchard and the owner gave me some logs. I had these cut into boards and dried them in my garage. They bowed real real real bad and I actually straigthened them by gluing up opposite bowed ends using a joint bit in a router. The end product needed some hand planing, but not much, the job pictured below.