Let's remove the 2-track tape deck from the equation so the whole tape hiss thing isn't part of it.
Take the "raw" tracks ITB...without any ITB processing...and do just basic ITB mixing/summing.
Then take the same "raw" ITB tracks and bring them individually D/A out to your analog console and again do no processing, just basic mixing/summing (and/or do it as stems to a summing box if you have no console).
Compare them.
That should be a comparison of just the mixing summing between the DAW and the analog console (or summing box).
Now take a mix that is done completely ITB.
Then take the "raw" tracks (NO ITB processing) that make up that ITB mix, but bring them out individually D/A from the DAW into an analog console for mixing, and also do all your processing with analog outboard gear.
Compare them.
That should be a comparison of the mixing summing AND the processing between the ITB and OTB mix.
Any sonic differences between any of those four mixes?
I don't think it's a question of digital "shrinking" the soundstage...rather more so that some folks hear a bit of a bigger (aka 3-D, organic, lifelike) soundstage with the analog sums/mixes. I've heard it with my ITB and OTB rigs....minor, but there. I prefer to mix OTB, but still edit, comp and do some spot processing ITB before the OTB mix.
Yes, like Jay said, the gear quality makes a difference in both analog and digital, and you really need the complete ITB and OTB rigs in all the scenarios above to do your own comparisons...otherwise you end up just guessing and/or assuming how things really sound based on other people's comments.
I'm not sure how many folks in the home-rec world have that capability in their studios to do that, and to compare ITB to OTB mixes, with and without ITB or analog processing...etc.
I've seen high-end pros with serious analog and/or digital studios lean one way or the other. Some are 100% ITB and loving it, while others swear that unless you can hear a complete analog OTB mix, you really don't know how good it can be.
I don't think there can be a truly analytical and accurate way to measure and prove anything on either side.
But you know...I don't think that is important and neither is the need to argue the different views ad nauseum.
Each person needs to make their own judgments based on the gear/rig they have...and then go with what they think is best.
If you only have an ITB rig...don't sweat the analog crowd's claims.
If you love analog only and don't use digital...don't sweat the ITB claims.
If you found a way to run a hybrid digital/analog setup...fine tune it to its limits and don't sweat either.
