The most widely used Gita is the one which was commented by Shankaracharya and is probably the oldest and has 700 verses. Even if we consider 745 Shlokas for the sake of argument, Majority essence of Gita is already covered in 700 Shlokas and rest Shlokas hardly give any additional meaning or change context. I will just quote few Indologists now.
Indologist Bhattacharya in his "Original Bhagavadgita Complete with 745 Verses" on page 21-22 says -
The message conveyed by Bhagavadgita is authentic and not very much
different from original version with 745 verses except that the later
has missing verses and there are some minor alterations in words here
Dr Pusalker in his work "Studies in Epics and Puranas", on page 144 says -
It is indeed curios how the Bhagavad-Gita presents such a relatively
fixed consistent text without any noteworthy variation for the last
1200 years. The current text contains 700 stanzas, there being to
other texts with 714 and 745 stanzas. The additional stanzas affect no
material addition; nor do they create any difference in the teaching
or add any new topic or argument.
Scholar Upadhyaya in his work of 1998 page 10-122 says -
Variant manuscripts of the Gita have been found on Indian
subcontinent. Unlike enormous variations in remaining sections of
surviving Mahabharata manuscripts, the Gita manuscripts show only
minor variations and meaning is the same.
Robert N Minor in his "Bhagavadgita : An Exegetical Commentary", 1982 says -
The current text of Bhagavad Gita is well preserved with relatively
few variant readings and none quite serious. This is remarkable in
light of numerous variants for the remainder of the Mahabharata, some
of which are serious. Secondary insertions are found in individual
manuscripts of Gita but they are clearly secondary. The number of
Stanzas in Gita is 700, a number conformed by Shankara and possibly
deliberatly chosen to prevent interpolations.
TMP Mahadevan in his "Original Bhagavad Gita" says -
Unless clear and unmistakable evidences are forthcoming, there is no
justification for regarding any verse of Gita as interpolation.
SC Roy in his "The Bhagavadgita and Modern Scholarship", 1941 says -
The text of the Gita has remained substantially unaltered in spite of
numberless interpolations that have taken place in other portions of
Mahabharata and hence theory of Interpolation in Gita is without any
The questioner showed that Mahabharata at one time mentions that Gita has 745 Verses. But this verse wasn't found in the critical edition of Mahabharata.
Lin Yutang in his work of 1964, in page 45-46 criticizes some of western bias and criticism of Gita. He says -
Any attempt by Western critics to separate serval strands of belief
from one another in the song and restore the original text is bound to
be foolish and ridiculous. Certain scholars have attempted foolish
task of determining Gita's original composition.