A reader has kindly pointed out that I was wrong to claim that the SESB contains “no account of variants in the textual tradition”. In fact, an apparatus criticus is available for both the Biblia Hebraica and the Nouum Testamentum Graece. (The Septuagint is morphologically tagged, but has no app. crit.)
Click on one of the diacritical marks which appear in the Greek or Hebrew text; the variants appear listed by biblical verse, with the MSS. in which (a) the variants and (b) the preferred readings are found. Each term in the display may then be further identified by hyperlink, moving the cursor over the place: (a) the exact meaning of the diacritical; (b) the MS. (date, library, contents). The verse in question is reiterated by moving the cursor over its reference (e.g. Matt. 2:9); clicking on the reference takes one back to the full biblical text.