>replace (fldname) with evaluate(replfldname)
>replace &fldname. with &replfldname.
>What would be more efficient?

The () is faster in this case, its also safer in situations (like COPY FILE) where there may be a space in the variable's value. The Named Expression would work, but the Macro would throw an error. I don't know if it applies to REPLACE, I've never tried it using the long field name of a database field.