If you think about how Brenizer (yes, the naming isn't really appropriate, but it's the name we've got) it's pretty much exactly like lashing your whatever-lens-you're-using (say, 85mm f/2.8) onto the front of a larger sensor (and magically getting it to cover the larger sensor).
Don't think of it as stitching the image "out there", think of it as stitching the image projected onto the sensor, and it should fall into place.
I dunno if it's one click now, but if it's not it will be. Lock focus and exposure, pan the camera around in a spiral, out from the desired center of the frame, taking pictures. Dump the whole mess into whatever software and press "go" and, poof, medium format image, or large format, whatever you like, as taken with whatever lens you had on the front. It's not any freakier than the old slit-scan pano cameras, which are the analog version of pretty much exactly the same thing.
I don't see that this introduces any noise, per se, and the quality doesn't do anything but go up.
Computational photography, it's the future!
Anyways, uh, this is pretty far afield from the OP, sorry!