Ethan pointed out to me that Babinet-principle based solvent correction is not always inferior to mask-based approach. My belief was based on some old observations which were in fact made prior to mask implementation in refmac and thus not exactly side-by-side comparisons. I hereby recant my prior statement, as I have seen the light in form of the R/Rfree dropping 0.5% for a particular model/dataset when switching from mask to Babinet.
Cheers, Ed. -- "I'd jump in myself, if I weren't so good at whistling." Julian, King of Lemurs