I backsweeten few wines and haven't experienced problems with sorbate. I read research papers for information.I have been making wine and doing MLF for awhile and have never found that k-sorbate adds off flavors in reds - have you had that experience? @winemaker81, have you had that issue? I ask because k-sorbate is a widely-used ingredient so easy to get and work with. K-sorbate is what I use when back-sweetening.
My risk tolerance for my wines is low, so I don't take unnecessary chances.