...In the meantime, if you will do the reverse-shift technique with your TS-E lens (if you have an L bracket), then you can keep your file in 16 bit and align the images manually and just erase away the seam - if done correctly, it only takes a minute or two and the results are great, and you've got a 16 bit file...
For those interested in "reverse shifting", the technique is explained at the bottom of this
article.Francois