Quickly looking at this, I found one infrequent word which LSJ marks as an LXX-specific case: the word πρόσταγμα occurring in Dan 9:10. That word is under several, all revised/supplemented, entries.
It seems that a number of entries included in the first edition of the supplement were drawn from the vocabulary of the LXX, and some of these were criticized for introducing new, potentially questionable senses for various words. See J. A. L. Lee, "A Note on Septuagint Material in the Supplement to Liddell and Scott," Glotta 47 (1969), 234-242.
One would do wise work to consult Muraoka and Tov's comments regarding the use of LSJ for LXX lexicography.
Certainly... however, it's important to note that both Muraoka and Tov have been involved with other lexical projects (Muraoka with his A Greek-English Lexicon of the Septuagint, and Tov with Lust, Eynikel. and Hauspie's A Greek-English Lexicon of the Septuagint, which was born out of the CATSS project he headed with Robert Kraft). So, neither one is an impartial, outside observer. As we would say in Virginia, they both have dogs in this fight.
In sum, LSJ's classical focus means that it may not be the ideal choice if you're in search of a single Greek dictionary, particularly if your interest is limited to biblical studies. (On the other hand, if you want the dictionary with the broadest coverage, then it's the clear winner.) In my opinion, it's an excellent resource to pair with BDAG and/or LEH, especially at the current sale price.