I also use nikons. My Rollei is the "T" model with a Tessar lens, in terms of coating probably similar to your Xenar.
I find it quite a bit "cooler" (i.e. bluer) than my Nikon lenses when using transparancy film. An 81B is usually needed to add warmth to colour tranny film shot in the Rollei.
I cannot comment on this. It's at least 4 year I shoot my last colour film. For color work I usually use a D200 digital. Anyway 95% of my shots are B&W on film. My comment was more on the color of the coating.